# Square hole and wood screw threads in metal - NT/OT



## Semper Vaporo (Jan 2, 2008)

If I were Norm Abram and working with wood, I could use a 1/2" square chisel in my mortising machine to drill a square hole... 

But I am not Norm, and I my stock is a 9" length of 1"x1.25" aluminium bar and don't have a mortising machine, anyway.

I do have a small mill, but lack severely in talent at using it.

How would you go about creating a 1/2-inch square hole in an aluminium bar? The corners can be radiused at maybe 1/32-inch.

I know there are elaborate computer controlled setups that can make hex heads on a lathe and I am sure there are EXPENSIVE attachments that I could get on a computer controlled mill, but I also lack money and I only intended to do this just once. I tried drilling a 1/2" round hole and wearing my elbows out with a file trying to put square corners in the round hole. It worked... kind of... but the fit was extremely poor on the square shaft (I tended to take too much off with the file).

I considered drilling a 1/16 inch diameter hole in each corner, offset by 1/32 from each edge of the intended hole), then drilling a 3/16 inch hole offset by 3/32 from each edge and then drill a 1/2 inch hole in the center... all using the mill for rigidity (I know I could not drill straight/parallel holes manually... let alone hit the correct place!). I figure I'd have less filing to do that way. 

But I have found in the past that small drill bits tend to wander and I doubt if the small holes will end up parallel (i.e.: the distance between the exit holes will not be the same as the distance between the entry points). Is there a way to improve the chances of getting the holes parallel?

To compound things the hole will not be perpenducular to the flat sides of the aluminium bar and thus the depth of the hole will be about 1.5 inches (i.e.: I need a drill bit that is slightly over 1.5 inches long to go through the bar from one side to the other at the intended angle.


Anyway, once that is done...

I need to put wood screw threads in a round hole in the same piece of aluminium. The major diameter is 0.218" and the root/shaft diameter is 0.160" at 10 tpi. The thread width at the root is only 0.032" so there is a flat shaft at the root of the threads between them of 0.068".

Are their "taps" available for cutting wood screw threads in metal?


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## xo18thfa (Jan 2, 2008)

The best bet may be take it to a real machinist shop and have them run a broach thru it. A broach is like a mega heavy duty cutting square file that they drive thru a pilot hole with an arbor press. Or maybe try to fabricate that part with other bar stock, leaving the square hole where you need it. Weld. solder, bolt together


I checked all my sources but could not find anything to tap those holes for a wood screw. .218" is very close to a #12 machine screw, but the coarsest thread I could find is 20 TPI. 


What might be worth an experiment is to drill a 3/8" hole and drive in a length of oak wooden dowel pin, then run the screws into that. The screw will expand the wood and make a very tight fit. I have done this into concrete and it makes a pretty solid anchor. 


Not much help.


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## Semper Vaporo (Jan 2, 2008)

Thanks Bob, the wooden dowel in a larger hole might just be the answer. I have considered filing a slot along the length of a hardened wood screw and try to use it to cut the threads. Might have to start with a small screw with the same thread pitch and work my up to the correct size.

After I posted the questions I remembered the line from the Bloom County comic wherein Opus was asking questions at the information desk of the Library..., 

"Look it up yourself, mush for brains!" 

So I did a lot of web searching last night. 

Learned a lot, but not much of any help in how to do what I want, in a way that I am capable of doing. 

"Rotary broaching" is kinda neat for making odd shaped holes as well as external shapes yet still using a lathe to spin the work (or the bit!)... but I could not find any prices for purchasing such devices, so given that the adage is, "if you have to ask the price, you can't afford it", I decided to try using a lathe bit as a broach to square up the corners after I do the 4 small holes in the corners and one big one in the middle. Maybe my mill will be strong enough to use as an arbor press to shove it through. Maybe lots of little bites will be do-able without breaking something.

I was just hoping that someone here would have some really brilliant idea (like using the dowel, thank again!) before I wandered down into the dungeon to ruin yet another perfectly fine piece of metal.


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## Les (Feb 11, 2008)

Semp,

Before committing much comment, I'd like to see a pic or sketch of what you're trying to do.

Putting wood screw threads in aluminum??? Um, why would you want to do that? I'm asking nicely, not being a smarta*s. There are sheet metal screws out there that do a nearly interchangeable job, but you'd still have to make clearance holes, not cut threads.

If you have a mill, you have all you need to put that offset hole (not parallel to edges) in that piece. If you think that's outside your skill level, here's a good chance to bring it into your bag 'o tricks. Will your mill tilt to the correct angle? Will the workpiece clear the column? If so, you're in like Flynn. If it won't things are harder.

As for using your mill as a sort of arbor to push a lathe bit down the corners, please don't. You run a huge risk of springing something irreplaceable.

To get parallel holes using a drill bit on an angle of entry--if I understand--you need to pre-drill oversize diameter from a vertical plane deep enough to give the bits (both of 'em) an equal bite, and don't use a lot of pressure. Below a certain diameter, drill bits wander for a lot of reasons.

Lastly, though I don't know what you're making, prehaps a redesign might be in order?

Lastly again, your first inclination was probably the best. Just don't file so much between fits, next time.


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## Les (Feb 11, 2008)

SEmper wrote: '....I know there are elaborate computer controlled setups that can make hex heads on a lathe....'

You have a mill. Get yourself a supply of some suitable hex stock larger than the range of diameters of heads you want to make. (Incidentally, on reread, if you want square headed bolts, just get some square stock while your out 'n about. Theory's all the same.)

Drill a hole in the end of a piece of hex stock on lathe. You MUST get it EXACTLY centered! Not hard, start with a center drill. And indicate it all the way around just in case your chuck's lying to you about being self-centering. Also, keep your chuck jaws clean enough to have lunch off of.

Drill and tap a 'gob' screw hole in side, to intersect workpiece hole. Put workpiece in hex fixture and tighten gob screw. (Allen screw; I like the Brit's term better).

Clamp fixture to mill table, put in a flat cutting bit, make passes to get to a pre-determined depth on one face, turn off mill, unclamp and move fixture over one face, and repeat all the way around. Wah-la-rus! You have a hex head. (If you're taking a lot of material off, do a few passes/face, don't try to hog it all off at once. And get in the mental habit of leaving yourself 0.010 or so for the oooppss! factor.) Nothing is more satisfying than to find out that one day, you don't need to leave that much anymore.

Note: you can turn the worpiece to a given diameter (Fewer hex blanks) first, then put it on the mill in the fixuture-- you can even leave it in the fixture in the lathe, though I wouldn't, or you can turn the head before you turn the body diameter. (If you use just a few sizes of blank stock, this'll keep you from having a lot of hex fixtures lying about, too.)

Remember, the tighter the tolerance you hold per step, the better the finished work will be. Tolerances are usually additive, only the blest get mutually-cancelling errrors.


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## Semper Vaporo (Jan 2, 2008)

Thanks for the words, Les.

My comment about cutting hex shapes on a lathe was just an example of what is so counterintuitive but quite possible on a lathe... not that I wanted to do such a thing. There are several YouTube videos of lathe work showing it done (yet frustratingly lacking in showing HOW it actually works). Fascinating none-the-less.

But, good news... I have managed to drill my square hole now! It is much better than my first attempt that I filled with the aluminium repair rods. That one was too big for several reasons, the main one being my idiocy of starting cutting before I thoroughly knew what the end result was supposed to be. (Redesign on the fly!







)

To make my work a bit harder, I decided to make the square hole a blind one (i.e.: not all the way through!). That decision was based on two things. One is aesthetics. This is a handle on a shaft and the shaft visible in a through hole would not be very pretty... but the main reason is that I tried drilling some holes in some scrap and the drill bit wandered in the 1.25-inch thick material such that the exit holes were not in the exact same pattern as the entrance holes. This would make the square hole not so square. i.e.: Not uniform width (in either direction) along the length of the hole. Thus it would not only LOOK bad, but not grip the square shaft well either.

I drilled 4 holes about 3/4 inch deep and then put a side cutting mill bit in and moved the x/y table to mill the square shape. I had to take VERY shallow cuts to keep from bending the bit (1/8 inch) and had to stop frequently to clear chips out of the groove I was making. I moved the table in a clockwise direction so that the outside edge of the hole was done by conventional milling, which may have been backward from what I should have done. I think it may have made the bit bend toward the outside and that enlarged the hole a wee bit... but that was okay as the shaft is NOT exactly square anyway and is slightly over the 1/2 inch dimension that I thought is was, so SERENDIPITY saved the day on that count as I had to do a bit of shaving of the sides of the hole anyway to make it slightly bigger than what the mill made it.

Unfortunately, the mill bit was only 1/2 inch long so I could not make the hole 3/4 inch deep. Doubly-unfortunately, I failed to get the swarf out of the way often enough and managed to break my 1/8 inch mill bit before I was done.









So, to finish the hole, I drilled a 1/2 inch hole down the middle and then chain drilled 1/8 inch holes near the corners to remove more material left between the original corner holes and the middle 1/2 inch hole. DRAT, I managed to break my 1/8 inch bit doing that!







(I was not moving the table, only moving the bit vertically. I assume it got pulled sideways slipping into a part of the hole already there and then snagged the edge.)

So... then I went at it with a ball carving bit in a Dremel Moto-tool... working mostly blind while cutting because with the Moto-tool bit in the hole I could not see in the hole at the same time because the Moto-tool was in the way!

I then chucked a carbide lathe bit in the mill drill chuck (yes, horrors of horrors, a square lathe bit in a chuck designed to hold round drill bits!... shame on me!) I then hand held the chuck to keep the lathe bit cutting edge parallel to the side of the hole and shaved small amounts off the sides of the hole to try to flatten/square up the sides and make it a wee bit larger to fit the shaft I want to put it on.

I did some more Dremel work on it with a barrel carving bit (boy do I have lots of aluminium dust aaaaallllll over!) The handle now fits the shaft pretty well and I am pleased with it.









Now to try to drill the cross hole and thread it. I could use a different screw in order to tap the hole for machine threads, but the tip of the screw presently penetrates the square shaft into a threaded hole that is threaded with wood screw threads... I assume they were cut by the screw itself. I would prefer (because I am an idiot, I guess) to retain the wood screw that is presently used to hold the plastic handle (that I am replacing) on the square shaft. I have purchased several wood screws of the same size and thread type to see if I can make them into taps. So far I have filed a lengthwise groove in one of them to see if I an make the threads into a cutting edge. Maybe multiple screws done this way will last long enough to make the threads in the aluminium. I am going to try it on some scrap first to see what size pilot hole works best.

I really don't want to modify the square shaft if I can get away with it.

I am now headed off to the dungeon to see how well I can make taps! (As long as nobody has to play "Taps" when I am done!)


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## Les (Feb 11, 2008)

Where there's a will, there's a way....







Sheesh, that's a lotta work.









FWIW, try to use the biggest end cutting mill bit you have that will do the job. For the corner radii, use a smaller one to suit. A larger bit is stiffer--which I'm sure you know, but it's also a bit easier to keep up with what's going on. Use cutting oil.

Hang in there.


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## Semper Vaporo (Jan 2, 2008)

HA! Where there is a will there's usually some ne'er-do-well distant relatives waiting in the wings for the ol' man to croak!

Actually, I find all metal working to be a lot of work. Calculate and calculate to determine just where to start. Then create some sort of fixture to hold the raw chunk of metal in just the right position and ridgedly enough to not slip out of place (of fly off through the dungeon window or my head) nor vibrate such that the cut is not at the exact right place. Then insert the approprate bit/blade/whatever in the tool and position it to the correct cutting angle. Then lower it to the surface and verify that the tool will continue to travel in the intended direction without running into something else. Set a stop at the approprate place to limit the depth of cut and lock everything down except the one direction of travel that is to be made (x, y, or z). Then turn the tool on and "zip" yer done... now re-arrange everything to make the next cut. Sometimes the rearranging is merely locking down the present axis that is moving and releasing another axis, but other times it can require a complete dissassembly of all fixturing that I worked so hard at creating and starting over with some new setup. I work really hard at doing everything possible that can be done with one setup before switching things to the next one.

Woodworking is a whole lot more forgiving about a lot of this stuff. You can lay the workpiece on a sheet of rubber, and place a handheld router on it and slide it around by hand and as long as you are somewhat careful the wood stays on the workbench, the chips fly and you get a nice edge all around the workpiece. You just cannot do that with metal!!! Try that with metal and if you are pressing hard enough to keep the work piece from leaving the immediate vicinity upon contact with the router bit and you will not be able to move the router by hand!

Anyway to conclude my saga...

Apparently on the Rockwell hardness scale, hardware store wood screws are softer than aluminium!!!! I filed a slot lengthwise in the screw threads to give a cutting edge to the threads and a place for chips to go. In the aluminium, I drilled a 3/16-in hole (larger than the shank of the screw but smaller than the diameter over the threads). Then I chucked the screw (sans head) in my drill press and hand turned and fed the screw into the hole in the aluminium. I now have a relatively smooth shaft with a small lengthwise slot along it. Stripped the threads right off the screw! Barely left an impression in the aluminium.

Reamed the hole out some more with a tapered reamer (so there would be less material to remove and make it a bit easier to get it started) and tried another screw, this time I cut two lengthwise slots using a cut-off disk in the Dremel Moto-tool. Made a nice looking tap, but alas, it also ended up a fairly smooth shaft (with two slots in it).

Drilled the hole to 13/64-in. (according to my calipers the outside of the screw threads measures 0.203-in which is just shy of 13/64 by .000125). This time I did not drill quite to the bottom of the hole (where it enters the side of the square hole). The screw still will not slide into the hole; the threads are a bit rough and the whole screw has a bit of a trianglar cross section (both are typical of wood screws). But, with a good screwdriver I can force the screw in and what little bit it grips the walls of the hole is enough to help force the tip through the last little lip I left at the bottom. 

One of the fixture parts I made was a square shaft that I could clamp to the drill press table to hold the part I am making vertical to drill the hole in the end. I had to move the table to the side because neither my drill press nor my mill is tall enough to put the part in it vertically and still get a drill bit in the chuck. Making that part took extra time and is not a part of the finished product and will probably never see any use in the future. At least I am getting one more use of it... I clamped it to a door frame down in the dungeon to hold the part out so I can paint it. First coat is on, and I'll give it a second coat tonight and a third tomorrow morning.


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## Les (Feb 11, 2008)

Posted By Semper Vaporo on 22 Jul 2009 05:19 PM 
HA! Where there is a will there's usually some ne'er-do-well distant relatives waiting in the wings for the ol' man to croak!

Actually, I find all metal working to be a lot of work.

/// Yeah, it sounds like it....









Calculate and calculate to determine just where to start.

/// Experience will help here.

Then create some sort of fixture to hold the raw chunk of metal in just the right position and ridgedly enough to not slip out of place (of fly off through the dungeon window or my head) nor vibrate such that the cut is not at the exact right place.

/// Weellll ... you don't always have to create a fixture: what you do is machine a 'tooling lug' on one portion of your raw stock that you deem most expendable. Either lathe or mill, you need at least two flat surfaces normal to each other. Here's where a good mill vise is worth its weight in gold--and costs like it, too. I've had only a few things slip out of a chuck or get pulled out of a vise, and they slow down fast and just make a 'clunk' on the floor, or rattle around on the machine for a second. These machines aren't big enough to impart a lot of angular velocity to something heavy enough to hurt you. Vibrations must be looked into instantly, caused determined (often too much speed on tool, or work turning too fast in lathe) or any of a dozen small things. Once I spent part of the morning milling a piece to suit, only to find I'd forgotten to tighten the vise hold-down nuts. It all came out okay, so I shrugged. Rather lucky than good, any day.

Then insert the approprate bit/blade/whatever in the tool and position it to the correct cutting angle. Then lower it to the surface and verify that the tool will continue to travel in the intended direction without running into something else.

///The first cut should be a 'skimmer', just enough material removed to show the tool passed thru that region. For a long time I kept misjudging the amount of distance to leave so I didn't crash the chuck into the headstock. And any number of times I got my knuckles rapped by the chuck jaws, which stick out on occasion.

Set a stop at the approprate place to limit the depth of cut and lock everything down except the one direction of travel that is to be made (x, y, or z).

/// I rarely used the z feed, unless boring. But I was using a knee mill, not a hobby jobby.

Then turn the tool on and "zip" yer done... now re-arrange everything to make the next cut. Sometimes the rearranging is merely locking down the present axis that is moving and releasing another axis, but other times it can require a complete dissassembly of all fixturing that I worked so hard at creating and starting over with some new setup. I work really hard at doing everything possible that can be done with one setup before switching things to the next one.

/// Yup, that's the right way.

Woodworking is a whole lot more forgiving about a lot of this stuff. You can lay the workpiece on a sheet of rubber, and place a handheld router on it and slide it around by hand and as long as you are somewhat careful the wood stays on the workbench, the chips fly and you get a nice edge all around the workpiece.

/// That makes me shudder to think of doing that. Of course, I'm no fan of routers, either. But when I use one, the wood is fastened down somehow. Woodworking has no real tolerances, compared to machining.

You just cannot do that with metal!!! Try that with metal and if you are pressing hard enough to keep the work piece from leaving the immediate vicinity upon contact with the router bit and you will not be able to move the router by hand!

/// Never try to work metal with a router. Never. People say they do it, but one day the world will go to **** in just a fraction of a second and give new meaning to the term, "Aw, ****!" A router bit turns ~ 25K rpm. Figure an average edging bit is in the half-inch diameter range. Now do the math and see what the SFPM (surface feet per minute) is, and you'll be amazed.

Anyway to conclude my saga...

Apparently on the Rockwell hardness scale, hardware store wood screws are softer than aluminium!!!! I filed a slot lengthwise in the screw threads to give a cutting edge to the threads and a place for chips to go. In the aluminium, I drilled a 3/16-in hole (larger than the shank of the screw but smaller than the diameter over the threads). Then I chucked the screw (sans head) in my drill press and hand turned and fed the screw into the hole in the aluminium. I now have a relatively smooth shaft with a small lengthwise slot along it. Stripped the threads right off the screw! Barely left an impression in the aluminium.

/// Now you know why I suggested sheet metal screws--though some of them are crappy, too. You might've tried turning a coarse pitch piece of steel on the lathe and trying that--match the pitch as close as you can and hope for the best. I doubt it'll work, but hey....

Reamed the hole out some more with a tapered reamer (so there would be less material to remove and make it a bit easier to get it started) and tried another screw, this time I cut two lengthwise slots using a cut-off disk in the Dremel Moto-tool. Made a nice looking tap, but alas, it also ended up a fairly smooth shaft (with two slots in it).

/// Taps are quite hard. And brittle. It's not unknown to drop on on the floor and break it. That's why you can cut threads with 'em.

Drilled the hole to 13/64-in. (according to my calipers the outside of the screw threads measures 0.203-in which is just shy of 13/64 by .000125). This time I did not drill quite to the bottom of the hole (where it enters the side of the square hole). The screw still will not slide into the hole; the threads are a bit rough and the whole screw has a bit of a trianglar cross section (both are typical of wood screws). But, with a good screwdriver I can force the screw in and what little bit it grips the walls of the hole is enough to help force the tip through the last little lip I left at the bottom. 

One of the fixture parts I made was a square shaft that I could clamp to the drill press table to hold the part I am making vertical to drill the hole in the end. I had to move the table to the side because neither my drill press nor my mill is tall enough to put the part in it vertically and still get a drill bit in the chuck. Making that part took extra time and is not a part of the finished product and will probably never see any use in the future. At least I am getting one more use of it... I clamped it to a door frame down in the dungeon to hold the part out so I can paint it. First coat is on, and I'll give it a second coat tonight and a third tomorrow morning.

/// Hang onto that piece of aluminum: you'd be surprised at how soon it might be remade into a nother fixture. Sounds like you're trying, and that's the main thing.


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## Semper Vaporo (Jan 2, 2008)

Do you remember the "Mama Mama" jokes of the late '50's and early '60's? Especially the one that went like this:

"Mama, Mama, Why am I running around in circles?"

"Shut up, Junior, or I'll nail your other foot to the floor."

When I am using my lathe or mill I often feel like 'Junior' in that joke. I end up running in circles like I have one foot nailed to the floor.


I do have a good (I think) vice for my mill. It is sometimes too small and sometimes a bit big, but it does do the job as my primary fixture to hold a raw chunk of metal. But I have to get it in position on the mill table such that the clamps that hold it down (it does not have the ears at the bottom for bolts) are not in the way of the mill quill and that I won't accidentally mill the jaws off. Further, I then have to make sure the raw stock is secured properly in the vice such that it cannot vibrate loose and is exposed such that I can get to the parts of it that need milling.

Most of the time what I am working on will fit in the vice (sometimes it won't open wide enough to hold the work piece) and usually the vertical space taken by the base and jaws is not so much that I cannot get the work piece and the mill bit to share the remaining space. But too often for my "druthers" one or more of those things goes wrong.

I also have a problem where the vice handle hangs out over the crank wheel of the mill table and it will often catch when I am not watching and can't figure out why it is suddenly so hard to move the other axis. So I removed one end of the handle so I can remove it from the vice lead-screw, but then it often falls out because it ended up in the wrong orientation when the vice has been tightened on the part. I think I picked that thing up off the floor 5 or 6 times setting up the mill for the part I just made. But I am getting better at remembering to look at it before I let go of it (at least I can watch to see where it lands on the floor and don't have to hunt for it!







).

When I first got the mill it came with large drill chuck to fit the R-8 taper quill. Yes, I understand that one should not use that kind of chuck for milling (it is to be used only for drilling) but the first thing I wanted to do with the mill was shave off the upper surface of a work piece. By the time I got the vice and drill chuck in place with a short mill bit in it, there was no room for the work piece... the bottom of the bit was below the surface that I wanted to lower the work piece to by milling it! (I now have a proper collet to hold the mill bit and it is lots more rigid for cutting sideways and leaves LOTS more room for the fixturing and work piece. It hangs down about 1/2 inch but the drill chuck hangs down 4 inches!)

I have also had to work with a piece that was too thin to properly grip in the vice and still have the upper surface above the jaws so the bit would not clip the vice jaws. So it had to be held down just with clamps around the edges and only on one end at a time so I could make it a wee bit thinner (surface plane it).

I find myself having to reposition the work piece too often, often before I have even taken the first swipe at it. Sometimes it is not held rigid enough or something is in the way or I have misread something and don't have it at the right angle in all axes for what I want to do.

I am getting better at it! So, yes I am trying... of course I once had a teacher tell me I was trying too... then she muttered "Very trying!" under her breath.

The square shaft fixture will end up back in the scrap bin I got it from and maybe will become the raw stock for the next project, or may be just one more thing for the kids to wonder about when they go through my junk.



I got another question. 

This is only the second time for the mill or lathe that I have had to take a piece of raw material and make a fixture from it... a fixture being something that does not become a part of the finished product but without which the finished product could not be produced (easily). I have often made a fixture from pre-made parts (1-2-3 blocks, vice, hold down clamps, etc.) but only once before had to fashion a particular shape from raw stock just for a fixture for milling something else.

Not limiting it to milling, one time I had to make a fixture, to make a fixture... I wanted two grooves in a board, 45-mm apart in an 8-ft radius curve as a fixture to hold two pre-curved rails in position upside-down while I slipped on plastic ties from the end. To make these grooves I had to make a 8-ft radius compass with a router on the end (yes, the compass was adjustable to make the two curves have a 45-mm difference in radius.) Thus I made a fixture from raw stock (1x4 boards) to make a fixture (a wide board with two uniform 8-ft radius curved grooves in it), neither of which has much use beyond their one time intended use.

I assume that it is fairly common to have to make a fixture from raw stock, but how often do you have to obtain, and cut on, raw stock to make a fixture to make yet another fixture? (Like my compass example.) 

Have you ever had to make a fixture, to make a fixture, to make a fixture? (I wonder how deep one might have occasion to go?)


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## Les (Feb 11, 2008)

Semper wrote '... I do have a good (I think) vice for my mill. It is sometimes too small and sometimes a bit big, but it does do the job as my primary fixture to hold a raw chunk of metal. But I have to get it in position on the mill table such that the clamps that hold it down (it does not have the ears at the bottom for bolts) are not in the way of the mill quill and that I won't accidentally mill the jaws off. '


That's a situation I'd want to correct because it's a built-in PIA, which you seem to be well aware of. Here's a solution: get a piece of 3/16 or so 6061 T6 aluminum flat plate and cut it to fit the footprint of the vise, with two wings to drill for mounting bolts. Then screw the vise to the plate in four-six places, enough to get a solid base. Now you have a mountable vise that won't exasperate you. For extra goodies, carefully measure and see if your bedway slots are dimensioned such that the vise, while bolted in one set, can have a bar mounted that will sit in the next slot or two up. You want a close, but not interference fit. Screw that toeplate to the vise mounting foot you just made. What it does is sorta automatically locate the vise and gives an extra surface against twist. You might have to cut a pair of T bolts short to clear the bottom of the throat of your vise, but if you do, you do. Now you can mount long stuff w/o interference.

Now, to keep from 'accidentially milling the jaws off', you need parallels. A set doesn't cost all that much, but if you're strapped, mill your own out of aluminum flat stock. Since I don't have a vise that small, I'm guessing at around 1/8" thick x perhaps 1/4" tall. What you do is lay one (or both of these in the vise throat as a riser for your workpiece, depending on how thick the piece is. If you can put in two, that's usually better. Make a set at whatever size you deem suitable to prop most of your work up above the jaws by 1/8" or so, or whatever makes you comfortable.

Here's a third trick for mounting raw stock to your mill: get a piece of plywood, probably no thicker than a 1/4" and use it for a pad. Attach your workpiece with step clamps. This is particularly useful for milling the edges of a plate or what have you. By judiciously indicating across your workpiece and adjusting the torque on the hold-downs, you can bring that sucker in amazingly level across the cut. Generally, with rough stock it doesn't matter. Obviously, the plywood pad can't be much larger than your stock, or there'd be no room for the clamps.

And... "Most of the time what I am working on will fit in the vice (sometimes it won't open wide enough to hold the work piece) and usually the vertical space taken by the base and jaws is not so much that I cannot get the work piece and the mill bit to share the remaining space. But too often for my "druthers" one or more of those things goes wrong."

Okay, I hate to say this, but you're working stock too big for your mill (vertical clearance) or too big for your vise. There are limits to mills without a table Z level control. Scale down your projects a tad. A bigger vise might not be out of place, either.

And... "I also have a problem where the vice handle hangs out over the crank wheel of the mill table and it will often catch when I am not watching and can't figure out why it is suddenly so hard to move the other axis."

That can be a serious PIA, plus a tad hazardous, in a non-blood-drawing-way. I'd make a knurled knob and replace the slider-bar thing, making the knob big, but not so it'll foul anything. Note: if you make the aluminum riser pad, it may get what you have out of the way of everything. Might want to size your vise pad thickness on a clearance dim. I don't know how high you'd have to go to get clearance, but you'd know.

While I'm thinking of it, when you're moving one axis, have the other dogged down. It helps with chatter and minor stuff, like drifting a few thousandths.

And..."I have also had to work with a piece that was too thin to properly grip in the vice and still have the upper surface above the jaws so the bit would not clip the vice jaws. So it had to be held down just with clamps around the edges and only on one end at a time so I could make it a wee bit thinner (surface plane it)..."

Never put a piece of thin flat stock in a vise horizontally. It will bend or deform, and you'll get all kinds of problems. That kind of milling you do on the mill bed, edges blocked with clamps, or hold-downs. That's a normal procedure. Just remember, there's a limit to how thin a piece you can fly-cut.

And..."I find myself having to reposition the work piece too often, often before I have even taken the first swipe at it. Sometimes it is not held rigid enough or something is in the way or I have misread something and don't have it at the right angle in all axes for what I want to do."

This is a normal part of the setup learning curve. I got in the habit very early on, of mounting the tool bit to avoid the clearance problems you mentioned. I bet I lost a quart of blood over the years, swiping the back of my hand or forearm on the edge of a sharp tool.

And...." This is only the second time for the mill or lathe that I have had to take a piece of raw material and make a fixture from it... a fixture being something that does not become a part of the finished product but without which the finished product could not be produced (easily). I have often made a fixture from pre-made parts (1-2-3 blocks, vice, hold down clamps, etc.) but only once before had to fashion a particular shape from raw stock just for a fixture for milling something else."

Making fixtures are part of the life. I cannot recall ever making a fixture to make a fixture, etc, but I suppose there's no real reason why one couldn't. I'd tend to think that most times, one fixture should do the trick for one part. The thing about fixtures are like grinding your own tool bits: you use 'em, modify 'em for the next job, etc, and you end up saving time--after you get a collection of ground bits and fixtures.

I'm saving for one of those MicroMark lathes with the SAE (Imperial threads on the leadscrews). But I'm going to try to save enough to get the whole schmear at one pass to avoid the frustration of setting up a job only to find I don't have the tooling for the job. At today's prices the total comes in at just around $2K. So much for a $500 mill, huh?









Les


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## Semper Vaporo (Jan 2, 2008)

Les,

Thanks for the advice.

I have the MicroMark lathe and at first I was seriously considering getting a "bigger and better" one (read that as I was looking at machines in the $4,000 to $9,000 range) and was getting sick from the sticker shock. Then a new friend arrived with a very nice live steam loco he had built. When I found out he had made it all from raw stock and raw castings, I was very interested to find out which lathe he had... turns out he has the same one I have! He saved me a lot of money (Thanks again Ted!) I have told that story here on MLS a couple of times before and I am sure you have read it.

I am certain you will find lots wrong with the machine, but I am also just as certain that you will know how to circumvent or compensate for all of its shortcommings and really enjoy using it and make very nice things with it (and thoroughly put me to same in the rapidity with which you will become familar with it, and how fast you will convert scrap into marvelous little parts (whereas I take nice clean stock and make scrap out of it!). In the right hands, it has a lot of capability.

There are lots of accessories that are really nice to have and they do increase the price of the machine over the "wow, that's cheap" price by 2 or 3 fold at least, depending on just how many of those cute accessories you "just have to have"! But, I found the mill to require a lot more "extras" than the lathe did just to get started. For the lathe all I "really" needed was a set of carbide bits to get started (for you, I supose you will just need a couple of pieces of HSS and a grinder... which I bet you already have), but the mill required collets, and specific mill bits required different collets... most were 3/8ths but I also have a fly-cutter set that are 1/2 inch. (and note the addition of the fly-cutter set!). I don't suspect that you will be making end mill bits from HSS yourself, though you will probably be sharpening them yourself. Then there was the clamping set and vise! 

Measuring and marking tools are needed anyway and can be shared between the two so I don't count them as "extras" and again, I bet you have them anyway.


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## Les (Feb 11, 2008)

Posted By Semper Vaporo on 23 Jul 2009 10:06 PM 
Les,

Thanks for the advice.

I have the MicroMark lathe and at first I was seriously considering getting a "bigger and better" one (read that as I was looking at machines in the $4,000 to $9,000 range) and was getting sick from the sticker shock. Then a new friend arrived with a very nice live steam loco he had built. When I found out he had made it all from raw stock and raw castings, I was very interested to find out which lathe he had... turns out he has the same one I have! He saved me a lot of money (Thanks again Ted!) I have told that story here on MLS a couple of times before and I am sure you have read it.

/// No, I haven't read that. But I have the memory of a mole, so I might have....

I am certain you will find lots wrong with the machine, but I am also just as certain that you will know how to circumvent or compensate for all of its shortcommings and really enjoy using it and make very nice things with it (and thoroughly put me to same in the rapidity with which you will become familar with it, and how fast you will convert scrap into marvelous little parts (whereas I take nice clean stock and make scrap out of it!). In the right hands, it has a lot of capability.

/// Well, don't down yourself. I've spent years in the trade, remember. That's why the loose tolerances and whatnot that people complain about don't bother me, the machines I was first assigned to were lucky they were still able to be turned on. Also, I'm pretty much aware of the fact that you can't buy 'skill' with money, you have to learn it, develop it. That's why I'm satisfied with the HF stuff (mainly--some is sheer junk and I get bit once in a great while). I just bought their little table saw and a drill bit sharpener, and I'm gonna post a 'review' here soon.

There are lots of accessories that are really nice to have and they do increase the price of the machine over the "wow, that's cheap" price by 2 or 3 fold at least, depending on just how many of those cute accessories you "just have to have"! 

Well, there's a really good point. At MAC, of course, I had access to anything I needed. With Micro, I'm gonna have to buy it all. And I've learned that the frustration of not having the tooling you need is not worth it, to me. (Sometimes at work, the indexing head was in use and I had to wait a few days, for example.) And with my income at the low end of a snake's undercarriage, I've decided to get it all, or none. And also, there's the price of a new tailstock for my lathe, the camlock one (better repeatable accuracy) and a couple of other things for the lathe, that are included in that price.

But, I found the mill to require a lot more "extras" than the lathe did just to get started. For the lathe all I "really" needed was a set of carbide bits to get started (for you, I supose you will just need a couple of pieces of HSS and a grinder... which I bet you already have), but the mill required collets, and specific mill bits required different collets... most were 3/8ths but I also have a fly-cutter set that are 1/2 inch. (and note the addition of the fly-cutter set!). I don't suspect that you will be making end mill bits from HSS yourself, though you will probably be sharpening them yourself. Then there was the clamping set and vise! 

/// Mills are more versatile (with the right tooling). I've already found a tiny fly-cutter set in a garage sale, and I do have some of my old tools left--parallels, etc. Speaking of which, yes, I can make and grind my own mill cutter bits. I have a metal chop saw, and the big HF industrial-shaped tool bit grinder, though that's a sheer luxury, but I'm gettin' old and don't have the strength/dexterity in my hands I used to have. As for the collet set, I'm torn between the 'best' one, and the 'starter' one, because the collet set and drawbar will also fit my lathe. In the case of the 'starter set', I'd first have to turn down a piece of stock to the nearest collet I have, when using them in the lathe. In the mill, of course, you only need what the size of your tool bits are. And you almost have to have a vise, or a couple of them if you want any flexibility. I kid myself that I'll get to see which one I never use. And you need, absolutely, the right angle blocks for mounting work.

Measuring and marking tools are needed anyway and can be shared between the two so I don't count them as "extras" and again, I bet you have them anyway.

/// Yeah, I do, though I had to buy one of those Mituoto(?--expensive dam' thing) dial calipers in metric/SAE, to save on aggravation.


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## Semper Vaporo (Jan 2, 2008)

Les:

See my comments (6th entry) in the thread: http://www.mylargescale.com/Communi...fault.aspx

A lot of the images from that thread are gone, but it still has some good info and references to other sites.

Also see:

http://www.mini-lathe.com/Default.htm

for good info on things you can do to modify the mini-lathe. I subscribed to the "Premium Content" for a year and downloaded everything I could get at the time (I think more has been added since and I may "join" again!) One of the things you can get is instructions on how to modify the standard tailstock to have the quick lock lever.

There is a link on the home page to a Mini-Mill companion site that also has good info about the various models and brands.


Also, for more accessories (and repair parts!), see: 

http://www.littlemachineshop.com/

I have purchased from them and liked what I got.

Oh yeah... see:

http://www.gadgetbuilder.com/index.html

for even more stuff about the Mini-lathe.


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## Les (Feb 11, 2008)

Thanks much for the addresses!

Little Machine Shop I'm aware of, but the rest I'm gonna go visit.


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