How do I make a square hole

[lazlo]

Jerry, I thought you were still looking for the Watts floating holder (which is very expensive)? Have you gotten yours to work? If so, could you post some holes you've bored with it?

The reason the Fuzzbean thread was so interesting (to me anyway) was that Watts drills were always mentioned as a machinist Urban Legend, but no one had ever seen one work, let alone how well it worked.

I agree with the problems associated with using a Mini-Mill to drive the Watts drill, but Fuzzbean's floating table design is pretty clever, and seems like it should be just as effective as allowing the head to float, like with the "authentic" Watts floating holder.

According to Fuzzbean's comments, the problem is that the Watts drill, unlike a true Reuleaux Triangle, just randomly bangs around inside the square template, so the metal removal is completely arbitrary. And the deeper the hole gets, the further the Watts shank (which is the part being constrained by the square template) is from the cutting tip, and the hole starts tapering off.

Even Harry Watts himself says you can't drill deeper than 2x the drill diameter with a Watts drill...

Harry tells me that the maximum recommended cutting depth is twice the size of the square,

The drills are $100 each, the square templates are $70 each, and the Watts floating toolholder is $340. Sinker EDM is looking more practical

[lazlo]

By the way, if anyone wants to try making a Reuleaux (or Watts) drill themselves, Fuzzbean posted a scan of what looks like an old Popular Mechanics article on how to make one:

http://www.homegunsmith.com/cgi-bin/...17441;p=144456

[J Tiers]

I think there is a rather fundamental difference between a big heavy table with workpiece and a moving drill in a far lighter holder.

Then also, the drilling of deep holes with ANY drill is often problematic. With a specialty drill, I would suppose that not to be magically different.

Fuzzbean used the drill without an essential part of the drilling system, in an underpowered machine, to drill a hole much deeper than the inventor recommends, and he got a bad result.....

Remind me again why we should be surprised at this, and why we should judge the system by that result?

Sinker EDM was not exactly a thriving portion of the business in 1914 or whatever.....

[J Tiers]

OK, here it is...

This hole may have taken 8 minutes, drilled just recently this morning after prior post, including setup, a slippy flat belt, cleaning said belt, and drilling the original round 5/16 hole, plus interruption by wife. It is a 1/2" square, and measures about 0.504 square, 0.550 deep.

I drilled in in the end of a piece of bar in the lathe because I have a setup for that.

[J Tiers]

Ran afoul of snippy forum rules about attachments and time between posts.....

Here is the last

BTW, the drill is not particularly sharp, I did hone it slightly before starting. Material is 1018. Lathe has 1/3 HP 3phase motor drive, direct via flat belt for this job.


Showing slight burr on edge

[TGTool]

It does have a wobble feature to it that may be difficult to copy.

It doesn't actually wobble in the way we think about loose fits wobbling. The centerline of rotation for the tools is at an angle to the centerline of rotation of the lathe. Since they're both rotating together once the tool contacts the work, it means that each corner of the broach contacts the work in turn essentially nibbling out the shape. That means that the broach tool then needs to have a back clearance of the offset angle plus a little.

Since they have the angular CL they also need a means to be set transversely a little to line the broach up with the hole center for tools of different lengths.

I've seen them made in a home shop kind of like a live center, but with a toolholder cavity instead of the 60 degree plug.

[Your Old Dog]

..........p.f.s.

[IOWOLF]

They wobble the way I think they wobble,Your definition of wobble May vary.

[lazlo]

OK, here it is...

This hole may have taken 8 minutes, drilled just recently this morning after prior post, including setup, a slippy flat belt, cleaning said belt, and drilling the original round 5/16 hole, plus interruption by wife. It is a 1/2" square, and measures about 0.504 square, 0.550 deep.

Nice job Jerry -- thanks for the pictures!

Did you find the floating holder on Ebay?

I was outbid by RKepler (Russ, here and on PM) on a complete Watts set about 2 months ago, but then again, he seems to outbid me on a lot of stuff

[J Tiers]

nope, got it at a sale.....

You do NOT want to know what I paid for it, but it was not much.

I think Fuzzbean just didn't go at it the right way. It is easy to use, and not even as noisy as you might think.

The floating table is no substitute, the holder is just a buzzin' around in the hole and chips come pouring out. Slower drilling than with a twist drill, but not by a lot.

The idea of a "random arbitrary" path seems wrong. I don't have any slow motion video of the actual holder and its movement, but the "impression by eye" is that a consistent path is taken by the drill. The tool marks at the bottom of the hole seem to confirm that impression. And I don't see how it could be avoided, since the ruleaux triangle only barely rotates inside the square.

BTW: the drills work a LOT better when the swarf can escape easily, as in a lathe. In a DP, the swarf would seriously compromise the operation, as the drill has no ability to move it out of the hole.