Harold Hall's Faceplate and Angle Plate Clamps

[Sailplane Driver]

I need some advice on setup and sequencing. I'm going to make Harold Hall's faceplate and angle plate clamps and would like some input on the best way to make the packing pieces and bushings. The rectangular stock items are pretty straight forward. Since there are lots of pieces - I plan on making four of each size and there are seven sizes plus washers - I would like to minimize setup and operations. For those who are not familiar with these, information including drawings can be found on Harold's site here: http://www.homews.co.uk/page39.html

The following is my best guess for sequence:

1. Drill the holes in the stock before cutting to length.
2. Cut the stock in the horizontal bandsaw.
3. Make a pot chuck, sized for the smallest piece, to hold the pieces.
4. Face one end, turn around and face to length. Chamfer edges.
5. Mill the step in the packing pieces.
6. Counter bore the longer packing pieces so there is less tapping to do.
7. Tap the packing pieces.

The holes will be different sizes for the packing pieces and the bushings. Should I drill the holes on the lathe or use the mill? I have two 12" long pieces of 1" diameter 12L14 if that makes any difference. I was thinking it would be easier on the lathe. I have a four-jaw so it wouldn't be too difficult to offset but I would have to cut the stock down since there would be too much overhang and the stock won't fit in my mini-lathe spindle. If I have to cut the stock down, it might be just as easy to drill on the mill.

Will a pot chuck size for 2mm be adequate to hold the longer pieces? How much of an overhang can I get by with for about 1.5mm grip? The alternative is to make some kind of spider for the longer pieces and grip them in the chuck.

Thanks guys.

 

[Silverbullet]

I'm not sure 12l 14 , is a good choice for clamps even small ones. You may have better luck buying a piece of flat stock in like a 4140 or another tool steel . A 32 , even 316 stainless should hold up to the pressure better. I think your steal may be alright for the studs. We use to call that leadloy years ago. And yes I cut and finish on the mill then drill with a vice set up with a stop to repeat position.

 

[Sailplane Driver]

Hey Silverbullet, the 12L14 is for round stock only. I figured it wouldn't be a big issue since it would be mostly in compression. I purchased 1018 for the rectangular clamps. I planned on using grade 5 1/4-28 bolts to get enough threads in the smaller packing pieces since metric bolts are a bit tougher to find here.

 

[Rex Walters]

Well, machinists are a pretty opinionated bunch, and you definitely have a lot more machining knowledge and experience than me (your post history is great),
but "this Hall fellow" is a pretty well respected author of a very large number of books and articles on model engineering and machining in general. I think he is or used to be the editor of the Model Engineers Workshop magazine in the U.K. To me, he's right up there with George H. Thomas.

What clamping method do you recommend for faceplate work? Mr. Hall's clamping system seems reasonably compact to to me. I'd be hard pressed to come up with anything more compact other than super-glue on freshly faced aluminum, but I'm still learning. (I use-super glue all the time for small one-off parts and light cuts, but its kind of a pain to clean up, especially with multiple setups.)

Seriously (no disrespect at all): if you have a better suggestion for faceplate clamping I'd also like to see it.

With respect to the original question, I'd recommend a "one part a time, one operation at a time" approach for a project like this (or almost any project). Definitely do not bore a deep hole through a long piece of stock as the first step before cutting pieces to length! Drill bits tend to wander, and deep boring jobs are a PITA anyway as you have to keep retracting the drill to extract chips. You can sometimes get away with drilling all the way through and then parting off multiple parts, but it's also easy to get into trouble that way.

For example, I'd machine the packing pieces as follows:

1. Chuck up a length of material in a three jaw chuck, with about 1/8" more than dimension A extending from the jaws.
2. Face.
3. Center drill, then M6 drill to a depth slightly deeper than dimension A.
4. Chamfer the bored hole slightly with a 90º countersink (to remove any burr).
5. Break the edges with a file.
6. Part off at dimension A. (Remember to break the inside edge with a file before parting all the way through.)
7. Extend more material, then repeat steps 2-8 for the number of parts desired. (Parts will already be spotted, though, so no need to center drill)
8. Flip and re-chuck each part to chamfer the hole on the other end with the countersink.

This completes the first operation, creating center-bored parts of the correct length. The second operation would be on the mill to bore the non-centered M6 hole. I'd do it as follows:

1. Insert the part in the vice. Use a v-block, parallels, and vice stop to repeatably hold each part in the same location.
2. Position the table to drill the offset hole.
3. Center drill, then M6 drill through the part.
4. Chamfer the drilled hole with a countersink.
5. Repeat steps 3 & 4 for each part.

The third operation is also on the mill to create the step. I'd create a super simple fixture out of aluminum to orient each part: just drill two M6 holes the correct distance apart in a piece of aluminum, then use pin gauges (or drill bits) slightly smaller than holes to align the parts before clamping them in the vise. After milling the step in each part, I'd do the final countersink chamfering and de-burring of the milled step edges by hand.

There are almost certainly more and better ways to do it, but that's how I'd approach the job. The idea is to make set-up changes between operations, as much as possible, rather than within an operation.

Hope this helps.
--
Rex

 

[mikey]

I suppose this sort of clamping arrangement is for those of us who don't own a milling machine. The bore in the example pic on Harold's site is a simple thing to do with a boring head. As Wreck implies, it would probably safer and more accurate as well.

 

[Wreck™Wreck]

Hey Wreck, thanks for a response. The lack of any input made me a bit sad.

If these clamps are not advisable, what do you suggest as an alternative?

Workable but not ideal, any length of boring bar extension is unwanted, keep the extension to a minimum. You have I suspect read that the rule of thumb is not to extend the work or tool more the 3 diameters, this is often impossible with boring operations. Boring tools are often made from more rigid materials for this reason, solid carbide shank bars are excellent for boring many diameters deep, anti vibration tooling also allows deep boring. This increases costs however.

In this case the excess threads and nuts are 2 or more bar diameters themselves, thread the clamps and bolt from the back allowing the bar to be held much deeper in the holder. At the very least use flat head screws.

It is possible that the author just threw it together for a photo.

 

[ghostdncr]

...thread the clamps and bolt from the back allowing the bar to be held much deeper in the holder. At the very least use flat head screws.

Good advice right here, I think. When using faceplates over the years, I've somewhat committed to making custom clamps for the job at hand. While more costly from a billable hour perspective, I've found things to run much smoother, safer, and generally make a better job of things doing it this way, in line with Wreck's advice. Oh, and I also radius or deeply chamfer those clamp edges. It took several "lessons" to learn this in my case, but well worth the little extra effort.

 

[Wreck™Wreck]

Well, machinists are a pretty opinionated bunch, and you definitely have a lot more machining knowledge and experience than me (your post history is great),
but "this Hall fellow" is a pretty well respected author of a very large number of books and articles on model engineering and machining in general. I think he is or used to be the editor of the Model Engineers Workshop magazine in the U.K. To me, he's right up there with George H. Thomas.

L. Ron Hubbard also wrote a book or three. He must be correct as it was published.

 

[Tony Wells]

Mr. Hall is a member here. We won't have any bashing of anyone, but especially one of our own. You are entitled to your opinion, of course, but not necessarily free to express it. If you don't believe me, re-read the rules. You agreed when you signed on here. First Amendment rights are not guaranteed in the private sector and can be waived.

 

[Wreck™Wreck]

Not disparaging anyone, merely pointing out that published books are not definitive in any way shape or form simply by being published.

Excellent use of your constitutional knowledge.