Off the wall idea

Hi All, I haven't posted in a while, so I thought I would go with something a little crazy.

Is anyone here familiar with Watt Tooling? It's pretty old school stuff for making not round holes (square, hex, etc.) with non-CNC equipment. The company is still in business, Watts Brothers Tool Works in PA.

From what I have read the system uses odd number fluted cutters, such a 3 flutes for square hole, 5 for hex, and a plate with the appropriate shaped hole to guide the cutter. The cutter sort of wobbles around the hole in the plate and ends up cutting the proper hole.

So my weird idea is that one of the super smart programmers here on the board could figure out the proper tool path for a cutter to follow the same path that the plate makes the Watts cutter follow.

The disadvantage of the Watts tooling is you need a different plate and cutter for every shape and size you need to cut, but the only need for the CNC version would be different diameter end mills for different sized holes.

Anyway, that's my idea, so feel free to fire at will!

Terry

I don't think this works with helical fluting, it would be straight flutes like a reamer.

Indexable tools are good for stuff like this.

Not to rain on your parade here, but it's pretty easy to make any hole shape you want with a CNC. You only need to use an end mill that is smaller than the hole size and that will make the desired corner radius. Just program the tool path and press GO.

I believe you are right about the straight flute cutters, the pics I've seen show those, and the geometry of the cut probably requires it.

Of course I know you you can cut non round holes already with CNC, but the corner radius is limited to the size of the tool, so tight corners require small tools, then you get into the whole depth of cut-tools diameter issue. The Watts tools cut very tight radii with tools close to the size of the hole.

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Originally Posted by MFchief

I believe you are right about the straight flute cutters, the pics I've seen show those, and the geometry of the cut probably requires it.

Of course I know you you can cut non round holes already with CNC, but the corner radius is limited to the size of the tool, so tight corners require small tools, then you get into the whole depth of cut-tools diameter issue. The Watts tools cut very tight radii with tools close to the size of the hole.

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Tormach sells a roto broach that cuts squares or other shaped holes. Is this what your describing or something similar

In order for your idea to actually work you need straight fluted cutters *and* the table XY motion *has* to be slaved to the rotational angle of the spindle. I suspect that the Tormach table movement speed is not capable of such high accelerations and the spindle is certainly not indexed sufficiently to slave the XY movements to the spindle angle in any case.

Well, I did say it was a weird idea, just thought it would be cool if someone could pull it off,

hy :) you mean this ?

https://www.youtube.com/watch?v=Jwk1FOj2xtE

https://www.youtube.com/watch?v=bA0PSNSwD3k&t=2s

...physics of machining is the only limits of what if, we try something different. Cost vs what if. Pull broaches are special build machines for splines are good example made for production for a reason, its faster, but cost more

DJ

Well, guess I wasn't crazy after all, but darn it, they stole my idea!

Thanks for the video's deadly kitten.

It is a nice video, though I still wonder the value of this method. That's a very low speed for the spindle and they are only cutting brass. If the process doesn't work in steel without a ridiculous machine then it's not a very efficacious process, even if it's efficient.

The use of a broach is still possible in your Tormach I'd think, and these can just be obtained. It still requires indexing, but it doesn't require spindle rotation under translation and so the speed is limited by your typical limits, ie machine stiffness, motion limits, load capacity on the motion (z-axis, safe down-force you can apply with the spindle).

I agree, it doesn't look too suitable for any kind of production, especially in tough materials. There are better, higher speed methods.

I just kind of like the clever way our predecessors found to solve problems before they had computers to help. So I thought there must be away to update the solution with modern tools.

Thanks again for taking the time to show me the vids you found.

hy mfchief :) i can program those without worries, but to make them run, is required a machine spec that will sync spindle phase with linear motion

such a spec is a basic foundation for other similar operations, like turning inside a mill, or excentric/cam turning inside a lathe; if such a spec is missing, then :
... at least for mills, there are after market solutions, like those developed by d'andrea italia
... at least for open arhitecture cnc's, like those arduino/linux driven, it can be implemented, with low cost, by the developer

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you need straight fluted cutters

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yes, but even more, you can actually calculate how much angle helix is allowed, so to still deliver the shape, within tolerance

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The use of a broach is still possible in your Tormach I'd think, and these can just be obtained

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it is, and even more, one can use a rough and a finish broach; also, such broaches can be manufactured in house; the tricky part with them is alignment inside toolholder, inside the spindle head, and not their machining conditions :)

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I just kind of like the clever way our predecessors found to solve problems before they had computers

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all cad algorithms are there before the 80s; nowadays, is only a facelift, repackaging the old release, some fancy addons, proprietary formats, etc / kindly :)

Thinking slightly further off the wall:
Rather than needing a machine with spindle sync you could mount your 4th axis on the mill table, lock the spindle to prevent rotation and rotate the A-axis instead of the spindle to cut.

I know Rube Goldberg would be proud of us if he were alive today. :)

Using a single flute cutter to make a hex pocket: https://www.youtube.com/watch?v=WPTcc-0FIaM

And lots more videos from the same clever person: https://www.youtube.com/user/samcoinc/videos

hy guys :) good idea kstrauss, with using the 4th axis

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Anyway, that's my idea

I know Rube Goldberg would be proud of us if he were alive today

And lots more videos from the same clever person

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sooner or later, same idea will emerge in persons that do not know eachother, or they live in different generations :) this is how things work

in other words, there is a spark in all of us / kindly :)

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Originally Posted by StrawberryBoi

It is a nice video, though I still wonder the value of this method. That's a very low speed for the spindle and they are only cutting brass. If the process doesn't work in steel without a ridiculous machine then it's not a very efficacious process, even if it's efficient.

The use of a broach is still possible in your Tormach I'd think, and these can just be obtained. It still requires indexing, but it doesn't require spindle rotation under translation and so the speed is limited by your typical limits, ie machine stiffness, motion limits, load capacity on the motion (z-axis, safe down-force you can apply with the spindle).

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Broaching can be done without an indexing spindle on a vertical mill. I have such a device (bought on eBay) for my Tormach that allows for cutting keyways or any other internal shape (including internal gear teeth when used with a rotary table). It is a Volstro Shaper/Slotter (originally made for Bridgeport mills). Note that this does not apply axial forces to the spindle:
https://www.ebay.com/itm/29432530957...p2047675.l2557 (Scroll down the page.)

Not wishing to pay for a proper slotter, I have been broaching using the Z-axis and with the spindle locked using the attachment shown here. Since I do not have an indexable spindle on my 770-3 rotation of the work was with a 4th axis rather than the spindle. The most recent use was to broach the grooves on some Multifix tool holders.