Hollowing Fixtures - How do they look?

[Matt Hutchinson]

Right now I am working out the kinks of the fixtures that need to be made to complete my ArtPrize submission.

There are 2 that need to be made. One is obviously a big honkin' hollowing rest, that will have a 23" inside working diameter. It'll be made of 1/2" plate steel....I hope. The second is a deep hollowing rest. Hopefully they will work as envisioned!

I don't know much about metal working so if there's something that needs changing please let me know. Thanks!

Hutch

[Tim Rinehart]

I 'think' I see where you are going, with the 3rd pic representing a rest that would protrude internal to the piece you are doing. It appears that you've made the internal support, with the vertical bars to prevent the boring bar from dropping off, but I haven't seen any pics of a boring bar.

This rig looks geared for a VERY deep object, but I'm assuming the opening is at least as big as that small piece that supports the boring bar.

I think it would help to see a 2D plan view of the piece, with the orientation of the hollowing rig to get at all surfaces you intend to cut.

This one is a unique approach, at least not one that I've come across in researching hollowing rigs.

[Matt Hutchinson]

Actually, in the third picture I will be to the right of the 'trapping' bars. The boring bar will go through the "trapping rest" onto the 6" tool rest pictured at the left. The single tube bolt-on extension on the right is what will be inside the open mouthed form shown below.

http://sawmillcreek.org/attachment.php?attachmentid=150347&stc=1&thumb=1&d=1273425509

This will be 5.5 feet long, and it maxes out the lathe's bed length. That's why the boring rig only has a single square base. I have to somehow get a tool rest, and a bar trapping setup, attached to the machine.

Hutch

P.S. The hollowing rest doesn't have a rollerblade wheel shown, but they will be attached to the sliding support arms as you would typically see in this type of steady rest.

[john taliaferro]

roller blade go away at about 200 per wheel. make the slot in the stablizer adjustable in size and hight i run down hill for vibration some times. my tool holder is simple a 1.5 solid and 3 90 degree welding pipe fittings . i use cup cutters or a hunter can get 2 feet verry carefully ,i am thinking you need to be around 2" solid and stick the rest in 2.5 ' that should get you close to 5' . i bet you could cheat and bore the bottom no one i know has 5' arms .

[Ryan Baker]

Wow. The 5.5 ft part certainly puts the scale on things. Good luck with it. You definitely will need a heavy-duty boring bar for that kind of depth. Looks like you are on the right track though.

John -- what do you mean by "roller blade go away at about 200 per wheel" ?

[Matt Hutchinson]

Ryan, I was kinda wondering the same thing. :)

John, do you have any pics of your setup? Thanks!!

Hutch

[Dick Strauss]

Matt,
What size opening do you expect for the final piece? You may want to weld a few pieces of round tube stock to act as cross-braces (at very slight angles to your main boring bar) to give it extra stiffness and better vibration dampening. I'd suggest something where there is a back mounting plate for your boring bar and the tubes are welded to the top and sides of the plate on one end and welded to your boring bar at the other end. If the tubes were different lengths, it would dampen vibrations considerably.

[Matt Hutchinson]

Dick, I am having a little trouble envisioning what you're describing. I get the idea of adding a piece for rigidity, but you lost me after that. :)

John, I don't plan on boring all the way to the bottom. Like you said, I will be hollowing the base 12 to 16 inches deep. So the bottom of the 'hollow' will maybe be 4' deep, but it could very well be even less than that.

Hutch

[Tim Rinehart]

Matt,
What is intention for hollowing the base out, just to save ease of boring?

As a piece that someone would want to buy, having a 'hollowed' base seems like it misses point of having a tall vase, without truly going to the bottom.
The hollowed base also creates a higher center of gravity, which adds to it's 'tipsy-ness'.

Just curious, I guess.
Regardless...this is a technical challenge that likely isn't without some compromise.


By the way, what size are you planning on for the square stock, including wall thickness assumption? Some overall lengths of the sections would help elicit some more thoughtful responses from forum, I think.
I look at it and say...hmmm, could work, but wonder if materials are adequate to address vibration, torque, etc. Details on boring bar needed also to understand supported/unsupported distances.

My other assumption is that this rig is used in a Jamieson captured fashion, but without use of a regular tool rest in front of the piece, as you've built that into the rig. Again...details on rest of rig would help.

[john taliaferro]

http://www.saabtuner.com/ i am sorry i skip words sometimes . the rooler blade wheeles i have will only do about 200 lb per wheel with a lot of cooling , its hard to see them go away cause they melt inside and squirts out the vent hole your not looking fer something like that with a log on. it was like whips of smoke, but wheel burned me when i touched. matt move the side wheeles down and and just put one on top. john t

[Matt Hutchinson]

Hey Tim,

I have decided to answer a couple of your questions in a new thread.

http://sawmillcreek.org/showthread.php?t=141578

You're right, I really should have said something about the dimensions. The "Jamieson" type rig, when it's bolted together, will be about 40.5" long from trapping bars to tool rest. The arm that will extend into the mouth of the piece is 20.5" long. The trapping bars are about 33" long. This fixture is primarily constructed of 2" tubular stock, the gauge of which is unknown. The trapping bars are 1.5" tubular stock. This is where my lack of knowledge comes in, cuz I simply am not sure what options I have available.

I am thinking I have 2 main options for the boring bar.

1. Use solid round stock 2" in diameter and 6-8 feet long.
2. Use heavy gauge 2" square tubular stock 6-8 feet long with bar stock welded on the end to hold the cutter.

Thanks!

Hutch

[Dick Strauss]

Matt,
Let me try again...maybe I'll do a better job of explaining this time...

You start off with a boring bar that is 5' long 2" in diameter and weld it to an 8"x8"x1/2" backing plate that is perpendicular to the bar. Then, weld a few pieces of tube steel diagonally at about 5-6 degrees to the boring bar about 1/4-1/3 the length of the boring length bar away from the cutter. The end of the tubes nearest the cutter could be crushed on one side to make them better match the shape of the boring bar. Weld the other end of the tubes to the plate after cutting the tube at a very slight 5* angle . All welded pieces should be above center on the boring system.

So on tube ends get welded to the boring bar at about the 4' mark (towards the cutter) and one end gets welded 3" off center from the boring bar to the backer plate.

[Matt Hutchinson]

I gotcha. I like that idea, but it might get a little tricky handling the boring bar. I will be riding that thing for a good 15-25 hrs I expect, and I don't know if there would be a great place to hold onto all that time. But maybe there could be another extension beyond the flat plate and bracing that could be held. Hmm.....interesting. Thanks!

Hutch