Speaking of Shop Made Wrenches/Tools & Not Waiting Around

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Bob La Londe 3 months ago

The Tormach Mill (not a large or fast mill) is used a lot for prepping blanks to go on the smaller faster mills. One thing it does is cut a round over for hinges. The best solid carbide tool I could find for the job with a small only 1/8 pilot (do the math) has a 5/8 shank. Initially I bought an ER32 TTS tool holder from Tormach as it was the only thing made that would hold a 5/8 for that machine and allow me to use it in the TTS system. I could take the ground 3/4 R8 collet out, and put in a 5/8 R8 collet, but that would require quite a lot of extra work to move the power draw bar (push pull) and install it. Then I would have to touch off tool height every time instead of recording a tool height for a tool in a "proper" holder int he tool table.

The ER32 3/4shank TTS tool holder was the best answer since I planned to use the 1/4 round over tool on every lead casting mold prepped on that machine. It didn't come with wrenches.

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I made a similar double ended set for my ER16 TTS and ER20 TTS tools as well. All the wrenches were made from 4140 HT. They could stand to be heat treated a little harder, but they hold up just fine as long as I don't let the tool slip off when I get in a hurry. I did remachine one, but totally my fault getting the wrenched jammed up between the flats and the threads. Actually it took more than a coupel screw ups to make me want to remake it, and I could still use it if I had to. Just be more careful.

Then I still didn't like it. The ER32 tool holder. It requires me to relocate the coolant nozzles every time I put it in and take it out. On its own probably not enough to discontinue its use since loclines move pretty easy, but its large size in every direction makes it crowded between other tools on my tool rack as well. Even the SEHT insert fly cutter can be turned so it doesn't hit other tools.

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I made a weld-on style TTS tool holder with the 3/4 TTS shank configuration, and then I walked the tool back to the grinder and put a flat on it. I don't recall if I used the surface grinder or the tool grinder. I've used both for grinding flats on round carbide tools. I probably used the D-bit grinder since I leave a diamond wheel on it. I am not all that great of a lathe operator, but I figured out how to make this holder all in one setup, so concentricity is pretty good.

I worked out a process for machining the inside hex on wrenches with just enough corner over cut so unless you look real close you can't even see the corners are over cut for hex point clearance. I also worked up a tool path for CNC cutting inside hexes that minimizes tool engagement in the corners by rounding into the a radius very slightly larger than the cutter, instead of the default most CAM programs give you when set to corner over cut that just goes straight into the corner. I did that when I was still selling speed handles for mill vises. The tiny end mill used for finish passes doesn't scream that way.

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I might bring those back when I get the rest of the machines up and running, but for now they take up to much time for a 20(ish) dollar part. I can cut sheets of them, but every one requires a second individual setup for the back side, and I sold the bandsaw I was using to separate them. Although, right now, while typing I did just come up with an idea to make full sheets in just two setups with some intermediate steps moving clamps. Maybe I will bring back the mill vise speed handles, but its no loss if I don't. Lots of people similar speed handles.

Anyway, making wrenches isn't all that hard. I just takes time and materials. Making wrenches as part of another tool like the wire bender adds to much time and material cost to the tool.

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Jim Wilkins 3 months ago

That is excellent work from a real machinist and toolmaker.

My stuff isn't show quality like yours, I make it to do the job and may clean it up later. Usually I use mild or annealed steel to preserve my taps and dies. Would 1144 be a good alternative that doesn't dull them?

A standard endmill can mill a sharp cornered internal hex in two parts, when milling one angle the flutes just barely kiss the corner two flats away. My application was a brake flare nut wrench that squeezed a deformed nut back hexagonal and began loosening it, so the hex opening is at the end of the pair of bars.

Swiss type files can give very neat results. I like the "hand" and "pillar" safe-edge styles for squaring a corner without cutting into the other side. The tops of vise jaws can serve as a straight flat filing guide.

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Bob La Londe 3 months ago

A very slight corner over cut doesn't require secondary setups, makes for faster production, and you know the best thing? Stuff holds up better if you engage the flats instead of the corners. They make special wrenches and sockets that exaggerate that principle.

I don't do a true corner over cut anyway, although the principle is the same. I a put a circle tangent at the corner, and then remove the part of the circle inside the hex and the part of the hex inside the circle. By making a finish pass with with a tool of radius slightly smaller than the radius of the remaining arc segment the tool wraps around into the corner instead of plunging sideways into the corner. No chirp. No chatter. Tools last a lot longer. Never 100% engagement that way.

100% engagement BAD unless you have an insanely rigid setup, and then if the tool can flex 100% engagement still BAD.

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Jim Wilkins 3 months ago

A very slight corner over cut doesn't require secondary setups, makes for faster production, and you know the best thing? Stuff holds up better if you engage the flats instead of the corners. They make special wrenches and sockets that exaggerate that principle.

I don't do a true corner over cut anyway, although the principle is the same. I a put a circle tangent at the corner, and then remove the part of the circle inside the hex and the part of the hex inside the circle. By making a finish pass with with a tool of radius slightly smaller than the radius of the remaining arc segment the tool wraps around into the corner instead of plunging sideways into the corner. No chirp. No chatter. Tools last a lot longer. Never 100% engagement that way.

100% engagement BAD unless you have an insanely rigid setup, and then if the tool can flex 100% engagement still BAD.

-- Bob La Londe CNC Molds N Stuff

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The difference is that you have and describe designing for CNC while I don't have even a DRO on my antique home machines, although I've designed for a Bridgeport and Hurco CNC mill. I mention the workarounds I use to get around my equipment's limitations, which are the same as current hobby level machines.

At Segway I got the machining jobs inappropriate for CNC such as modifying castings with no remaining reference surfaces and "see the pattern" for dimensioning.

The sharp square corners are mainly for control panel cutouts for rectangular electronic modules.

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've drilled small holes at the corners of hex wrench blanks to clear the points on the nut. Much of my work is for outdoors, vehicles etc, and I try to avoid damaging the plating on expensive parts. My lug nut sockets are a size larger with copper tubing inserts.

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Bob La Londe 3 months ago

Another approach to square corners suitable for manual milling and doable by eyeball is broaching.

For CNC milling its possible, but you need C axis spindle control for orientation. For manual milling you lay the toll against the flat and/or a block and nibble your way into the corner with a hand ground tool.

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Jim Wilkins 3 months ago

Another approach to square corners suitable for manual milling and doable by eyeball is broaching.

For CNC milling its possible, but you need C axis spindle control for orientation. For manual milling you lay the toll against the flat and/or a block and nibble your way into the corner with a hand ground tool.

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I've used the lathe to index and broach an internal hex in brass with an undersized Allen wrench ground to a sharp bevel on the end to cut one corner at a time. I forgot how I indexed with the 3-jaw, cutting with one jaw either straight up or down would do the 6 corners. My mill's spindle downfeed gears are warned to be too weak for broaching.

Blank HSS lathe bits ground to a cutting edge can shatter if hit too hard.

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Bob La Londe 3 months ago

Then there is the "expensive" CNC approach. (Can also be done with tilting fixtures on CNC or some manual machines).

I just saw a video this morning while enjoying my coffee from Titans of CNC where they used a 5 axis machine and a pointed chamfer tool.

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Its an eight and a half minute video so you may not want to waste that much of your time, but there is about a half minute or so of useful content embedded therein.

Generally I stay away from more complex setups whether done manually or by numerical control, as with every new variable there is a diminishing margin for error. Not that I don't do it if I have to (don't have 5 axis cnc) I just avoid it if there is at all any simpler method to achieve the goal.

I have a fixture plate and a couple modified spin indexers so I can mount them face to face for machining features on cylindrical parts using 3 axis methods. Once the plate is keyed to the table and the spin indexers are set in the groove the orientation is very good.

I also use a tilting vise from time to time, and relatively more recently picked up a CNCed rotab and a live (spins not powered) chuck for its matching tail stock to do similar operations without manually indexing.

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Speaking of Shop Made Wrenches/Tools & Not Waiting Around

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