Toolmakers Clamps (mistakes were made). [2048x1136 - 305KB]

173

• (+11/-0)

Toolmakers Clamps (mistakes were made). [2048x1136 - 305KB] (pic8.co)

Here's my first project on the new Milling Machine (Optimum MB4 clone), It's a pair of Toolmakers Clamps made from some rusty old 5/8" square bar I picked up from a scrap yard.

Here's the raw material (the round bar was later replaced with some newly acquired 12mm round that I forged the handle spirals on). Got to put my new horizontal bandsaw to use in this one too. https://pic8.co/sh/H7eurK.jpg

Step 1 was to square up the stock. Starting with one edge held against the fixed jaw of the vise (with a piece of soft wire between the other edge and the moving jaw) and only one corner resting on a parallel, I cleaned up one side. The piece was then rotated so the newly flat side was against the fixed jaw and the process repeated. The last face didn't need the wire on the moving jaw and could use two parallels as both clamped sides were flat and parallel. https://pic8.co/sh/Z9isLA.jpg

From the original ~16mmx16mm size, they were taken down to 12mm x 14mm. They were to be 100mm long, but ended up being 99mm long. This was because my set of end mills that I brought had an 18mm end mill in the spot that was labelled 16mm. Turned out, the shank of the mill was 16mm, but it was indeed an M18 bit. So, when I set the DRO to 108mm from the vise stop, I was expecting to take the end down to 100mm exactly, but instead got 99mm.

Holes were then drilled, the bottom bars receive two threaded holes, I used M7 x 1.0 thread, as this was a reasonably fine thread that had a slightly larger diameter than M6, and I also had ok looking taps and dies for it. https://pic8.co/sh/iQhfqM.jpg

The top pieces were a little more complex, the back hole was a blind, flat bottomed 5mm hole that was drilled with a 2-flute slotting drill to a depth of 6mm. The middle hole was clearance for M7 with a 10.5mm pocket that was 2mm deeper than the cutaway and a 1.5mm deep cutaway that would recess the retaining plate. A blind tapped M3 hole was also added to take a countersunk M3 screw that would hold down the retaining plate. https://pic8.co/sh/Q9lYvk.jpg

The biggest mistake here was that I, for some stupid reason, put the recess for the retaining plate on the wrong side of the middle hole. It was supposed to be behind it, which would leave more room for a shallower slope on the nose. That error constrained the angle that I could cut the nose, in the end not a big deal though. I also fucked up when milling the 10.5mm pocket. Since I don't have a 10.5mm end mill, and wanted a flat bottom, I plunged in with a 10mm, then moved around in a rectangle 0.25mm from the origin. But, I got my directions mixed up once, and accidentally took off more than I wanted, leaving a very thin wall thickness on one of the parts. Again, this is of no material consequence, but an important lesson to learn so I don't fuck up on something that is important.

To make the retaining brackets, I used an offcut of 25mm square tube. This had the benefit of being it's own clamping jig. First I milled in from the side and side milled down the wall thickness to about 1.5mm. Then I flipped it 90deg, milled out the main pocket, which was 7mm wide. Again, I don't have a 7mm end mill, so I did a similar thing, moving a 6mm end mill over 0.5mm each way to get the desired width. Then a 3mm hole was drilled for the screw. This was countersunk with a 5.5mm drill, as the screws I had had a very shallow bevel to them. Once the drilling was done, the 6mm end mill was used to cut slots to define their width, then the back was very carefully milled down until I had just a sliver holding them on, that I could break off easily. https://pic8.co/sh/gLIEOx.png

I originally turned down one of my bits of round bar and knurled a handle on it. Then I used my M7 die to cut the thread with it mounted in the lathe. But, since it was such a long thread, the die wandered around a bit, and the resulting thread was shithouse. I couldn't hold it straight in a collet chuck to do the remaining operations. I would need to make a new one. So, I decided that rather than just putting a knurl on the handles, like every single bought one that costs $20, I would forge a twist into some round bar to act as the grip.

To do this, I laid out the 4 places that I would need to twist. These were forged down square, then twisted in my leg vise. I don't usually get photos of that process as you need three hands just to do it, and you only have seconds to do it before it cools too much. https://pic8.co/sh/zXoIB3.jpg

Once forged, put centers in each end, turned a nominal size between the pairs of twists then cut them into individual segments. These could be held in the chuck and live center for turning down the rest of the features and single point threading. https://pic8.co/sh/13is4t.jpg

Once some cross holes were drilled in the handles, everything was done.

Here's an exploded view of all the parts (for one clamp): https://pic8.co/sh/g2d7PQ.jpg

They turned out really nice. They have an excellent feeling of quality to them, the threads and fits are crisp (some need a little wearing in). Probably still needs a little filing and sanding to take off a few last little burs, but overall they turned out well.

On to the next project....

Here's my first project on the new Milling Machine (Optimum MB4 clone), It's a pair of Toolmakers Clamps made from some rusty old 5/8" square bar I picked up from a scrap yard. Here's the raw material (the round bar was later replaced with some newly acquired 12mm round that I forged the handle spirals on). Got to put my new horizontal bandsaw to use in this one too. https://pic8.co/sh/H7eurK.jpg Step 1 was to square up the stock. Starting with one edge held against the fixed jaw of the vise (with a piece of soft wire between the other edge and the moving jaw) and only one corner resting on a parallel, I cleaned up one side. The piece was then rotated so the newly flat side was against the fixed jaw and the process repeated. The last face didn't need the wire on the moving jaw and could use two parallels as both clamped sides were flat and parallel. https://pic8.co/sh/Z9isLA.jpg From the original ~16mmx16mm size, they were taken down to 12mm x 14mm. They were to be 100mm long, but ended up being 99mm long. This was because my set of end mills that I brought had an 18mm end mill in the spot that was labelled 16mm. Turned out, the shank of the mill was 16mm, but it was indeed an M18 bit. So, when I set the DRO to 108mm from the vise stop, I was expecting to take the end down to 100mm exactly, but instead got 99mm. Holes were then drilled, the bottom bars receive two threaded holes, I used M7 x 1.0 thread, as this was a reasonably fine thread that had a slightly larger diameter than M6, and I also had ok looking taps and dies for it. https://pic8.co/sh/iQhfqM.jpg The top pieces were a little more complex, the back hole was a blind, flat bottomed 5mm hole that was drilled with a 2-flute slotting drill to a depth of 6mm. The middle hole was clearance for M7 with a 10.5mm pocket that was 2mm deeper than the cutaway and a 1.5mm deep cutaway that would recess the retaining plate. A blind tapped M3 hole was also added to take a countersunk M3 screw that would hold down the retaining plate. https://pic8.co/sh/Q9lYvk.jpg The biggest mistake here was that I, for some stupid reason, put the recess for the retaining plate on the wrong side of the middle hole. It was supposed to be behind it, which would leave more room for a shallower slope on the nose. That error constrained the angle that I could cut the nose, in the end not a big deal though. I also fucked up when milling the 10.5mm pocket. Since I don't have a 10.5mm end mill, and wanted a flat bottom, I plunged in with a 10mm, then moved around in a rectangle 0.25mm from the origin. But, I got my directions mixed up once, and accidentally took off more than I wanted, leaving a very thin wall thickness on one of the parts. Again, this is of no material consequence, but an important lesson to learn so I don't fuck up on something that is important. To make the retaining brackets, I used an offcut of 25mm square tube. This had the benefit of being it's own clamping jig. First I milled in from the side and side milled down the wall thickness to about 1.5mm. Then I flipped it 90deg, milled out the main pocket, which was 7mm wide. Again, I don't have a 7mm end mill, so I did a similar thing, moving a 6mm end mill over 0.5mm each way to get the desired width. Then a 3mm hole was drilled for the screw. This was countersunk with a 5.5mm drill, as the screws I had had a very shallow bevel to them. Once the drilling was done, the 6mm end mill was used to cut slots to define their width, then the back was very carefully milled down until I had just a sliver holding them on, that I could break off easily. https://pic8.co/sh/gLIEOx.png I originally turned down one of my bits of round bar and knurled a handle on it. Then I used my M7 die to cut the thread with it mounted in the lathe. But, since it was such a long thread, the die wandered around a bit, and the resulting thread was shithouse. I couldn't hold it straight in a collet chuck to do the remaining operations. I would need to make a new one. So, I decided that rather than just putting a knurl on the handles, like every single bought one that costs $20, I would forge a twist into some round bar to act as the grip. To do this, I laid out the 4 places that I would need to twist. These were forged down square, then twisted in my leg vise. I don't usually get photos of that process as you need three hands just to do it, and you only have seconds to do it before it cools too much. https://pic8.co/sh/zXoIB3.jpg Once forged, put centers in each end, turned a nominal size between the pairs of twists then cut them into individual segments. These could be held in the chuck and live center for turning down the rest of the features and single point threading. https://pic8.co/sh/13is4t.jpg Once some cross holes were drilled in the handles, everything was done. Here's an exploded view of all the parts (for one clamp): https://pic8.co/sh/g2d7PQ.jpg They turned out really nice. They have an excellent feeling of quality to them, the threads and fits are crisp (some need a little wearing in). Probably still needs a little filing and sanding to take off a few last little burs, but overall they turned out well. On to the next project....

[–] • 1 pt

You can make a tap for cutting threads in wood that has a different geometry and thread cutting dies for cutting threads on wood. I think the modern wooden threads are cut using a thread whirler, or a live tool in a lathe for internal threads, that's beyond my tech level though. For wooden threads, the larger they are the easier they are to cut generally. So something really big like a screw press thread can be cut, even by hand using chisels/gouges if necessary, as you go smaller, the scale of the grain of the wood has more and more impact. The good quality wooden threaded clamps would likely have used something like boxwood for the threads as that has a very fine structure and can be worked to fine details. For internal threads, I've had pretty good results down to even 20TPI (1/4 20) or a 1mm pitch (M6 x 1.0) when using steel threads into a hole tapped in wood.

Thinking about it, I think the best way to do external threads in wood in a home shop would be to use some sort of live tooling in the toolpost (a small router for instance) and use a tapered cutter to cut the threads, or mulitple passes at different angles. On a mill, you could do it with a dividing head to effectively spiral mill in a similar way, which would give you much more lee way in terms of pitches. Here's Tom Lipton doing something like what I'm thinking of in plastic as a test: https://www.youtube.com/watch?v=AVydTvwqmRs Tom uses electronics for the lead screw to dividing head linkage, but that can also be done mechanically.

Ah, yeah. The really old fashioned ones that have wooden threads in them. I was thinking of ones that use a metal thread with cylindrical nuts so they can be skewed and used to clamp strange angles as well as parallel. The mill is good for doing precision wood cutting, but spindle speeds aren't quite up with something like a wood router, so you can get issues with tear out if you're not careful. I've already done some work with wood on the mill. It greatly helps with accuracy, at least for the start of the holes you drill, but drill bits (particularly small ones) can wander. You can make a tap for cutting threads in wood that has a different geometry and thread cutting dies for cutting threads on wood. I think the modern wooden threads are cut using a thread whirler, or a live tool in a lathe for internal threads, that's beyond my tech level though. For wooden threads, the larger they are the easier they are to cut generally. So something really big like a screw press thread can be cut, even by hand using chisels/gouges if necessary, as you go smaller, the scale of the grain of the wood has more and more impact. The good quality wooden threaded clamps would likely have used something like boxwood for the threads as that has a very fine structure and can be worked to fine details. For internal threads, I've had pretty good results down to even 20TPI (1/4 20) or a 1mm pitch (M6 x 1.0) when using steel threads into a hole tapped in wood. Thinking about it, I think the best way to do external threads in wood in a home shop would be to use some sort of live tooling in the toolpost (a small router for instance) and use a tapered cutter to cut the threads, or mulitple passes at different angles. On a mill, you could do it with a dividing head to effectively spiral mill in a similar way, which would give you much more lee way in terms of pitches. Here's Tom Lipton doing something like what I'm thinking of in plastic as a test: https://www.youtube.com/watch?v=AVydTvwqmRs Tom uses electronics for the lead screw to dividing head linkage, but that can also be done mechanically.

[–] • 0 pt

Not at all as easy as I thought!

I wonder what they did 100 years ago? Machine dies that cut the threads into the wood as it was wound down a dowel? I have no idea.

For the internal threads, you would use a tap. For external threads, a tool called a Screw Box, which is basically a wooden block with handles on it, a hole half way through at the major diameter of the thread, the rest threaded. At the transition, there is a V shaped cutter, basically like a V gouge chisel, that takes a full depth cut of the threads. It's cutting across the grain, so needs to be really sharp to do a good job.

Here's a video from Roy Underhill (The Woodwright's Shop) from probably the 80s about doing just that: https://www.youtube.com/watch?v=BV4cADdZ6wY (for some reason, the episode repeats 3 times in this video, so it's really only 15min long or so).

I used to watch a lot of Roy Underhill years ago but I didn't remember seeing this episode. Very cool.Thanks for the link!

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