Hollowing rig questions

[Tom Baugues]

I have finally started to weld up a hollowing rig system. Today I welded up a "D-Arm" from 3/4" stainless steel shaft. I also welded up a back support rest....which brings me to my first question. I'm building a rig like this https://www.lylejamieson.com/tools/tool_howto.asp . It calls for a backrest of anywhere from 30-38" across. One place one his website he says 30-32" and another he says 38"...My question is....do I really need it that wide? In the case of 38" he states that it should have 10" in front of lathe and 28" in the rear.
I know some of you have made your back rests so that you can slide them forward and back and I may make mine that way too...just looking at my options. I'll get some photos of it all in the next couple of days.
I also will then be trying to figure out how to make the cutting tips. My boring bars will be 3/4" bar as well but I need to know how to attach the cutting tools to the tip of the bars.

[Vaughn McMillan]

Tom, I'd recommend making the back rest as wide as possible. You'll be glad to have the extra movement capability.

For mounting the tips, search the forum for a thread I started a couple years ago about making boring bars. I think the thread title is something like 'A boring day in the shop'. (I'd search for you, but I'm on my phone, so pasting links is a pain.)

[Tom Baugues]

Thanks Vaughn, I'll look it up.

[Bernie Weishapl]

I agree with Vaughn and would go around 36". You will be glad for the extra movement in the unit. Mine is around 34 1/2" and sometimes I wish I had a couple more inches.

[Tom Baugues]

I agree with Vaughn and would go around 36". You will be glad for the extra movement in the unit. Mine is around 34 1/2" and sometimes I wish I had a couple more inches.

I welded up my back rest at 32" however I still need to mount it to the base so maybe I'll come up with a way to slide it on the base forward and backward a few inches to give me that extra length. My lathe sits up against a wall and even at 32" I would still need to pull it away from the wall to use it. I thought I was just saving myself from having to pull it from the wall but I guess I just will have to do that when needed.

[Vaughn McMillan]

Thanks Vaughn, I'll look it up.

I found it, Tom...

http://familywoodworking.org/forums/...ad.php?t=13507

Note that in post #29 I make a correction on the size of the tool bits. They were 3/6" bits, not 1/4".

[Bernie Weishapl]

I hear your pain Tom. I had to move mine away from the wall a few inches.

[Tom Baugues]

I found it, Tom...

http://familywoodworking.org/forums/...ad.php?t=13507

Note that in post #29 I make a correction on the size of the tool bits. They were 3/6" bits, not 1/4".

Thanks Vaughn, that helps alot. I have quite a bit of stainless steel shaft here now of several different sizes to make tools with. I saved several old shafts from some machine repair work that I do. I should have enough for a dozen or so tools if needed. I'll now have to be on the look out for square HSS bits.

[Vaughn McMillan]

...I'll now have to be on the look out for square HSS bits.

Look no further...

http://www.use-enco.com/CGI/INSRAR?PMSECT=0000000747

Pick a size and material. In my experience, the HSS ones work just as well as the cobalt ones. (As I understand it, metalworking benefits from using the cobalt bits because they withstand high temps better. Cutting wood doesn't get the bits hot enough to make a difference.) I've bought the 2" or 3" long ones and cut them (snapped, actually) into two shorter bits.

[Bart Leetch]

I found it, Tom...

http://familywoodworking.org/forums/...ad.php?t=13507

Note that in post #29 I make a correction on the size of the tool bits. They were 3/6" bits, not 1/4".

I am supposing you meant 3/16?

And what is meant by back rest is it the part the back of the tool steel holder slides through that captures it & keeps it from twisting or turning?