Consistent way to clamp a large rim suggestions

[MicroMach]

We got a steady stream of customers that bring us all sized steel rims from farm/heavy equipment that often wants us to cut out a face and reweld new plate into it. Those plates are often 3/4 inch thick and air arc blasting is not an effective way of doing it , in this case we have a 28" rim that because it's slightly oval it will hit the way of our largest lathe , so we retrofitted rotary axis controlled by CNC for a slow rotation and want to use a horizontal mill to cut out the remaining of the plate inside. Customer almost always brings us rims with most of the plate cut out with a torch, but leaves about 3/4 edge that we need to cut out in order to put a new plate in.

We made a large 5ft faceplate to set on the rotary and then attach the rim. Although we can attach it at the bottom we need a consistent way to attach it on the bottom as well as the top since there's no way to put a steady rest and we encounter the issue with vibrations.

Open for suggestions on effective and repeatable clamp system/way to do it

 

[Ox]

IDK if this is of any help, but this is what we have on our big (30"?) rotary.

These bars was on it when we got it, and they work purty good.
The one half is drilled "through" so's to be bolted to the slots on the table.
Then the other half is all tapped.
They can all be slid in or out as needed.

Same thing only differ'nt than yours?





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I am Ox and I approve this post!

 

[Gearclash]

Seems to me any work of that nature would best be done on a vertical turret lathe.

 

[MicroMach]

IDK if this is of any help, but this is what we have on our big (30"?) rotary.

These bars was on it when we got it, and they work purty good.
The one half is drilled "through" so's to be bolted to the slots on the table.
Then the other half is all tapped.
They can all be slid in or out as needed.

Same thing only differ'nt than yours?


View attachment 408115


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I am Ox and I approve this post!

Kinda, our rims usually stick out pretty far out and there's an issue with vibration then

 

[MicroMach]

Seems to me any work of that nature would best be done on a vertical turret lathe.

we work with what we got, no vertical turret lathe available

 

[gbent]

Look up bolt on jaws or faceplate chuck jaws.

 

[Garwood]

Think outside the box.

Do you know the 3 R's of machining? They are Rigidity, Rigidity and Rigidity.

Your setup looks floppy.

Mount your big lathe chuck on the main HBM spindle. Stick your toolpost to the table. Then you can swing your wheel.

 

[MicroMach]

Think outside the box.

Do you know the 3 R's of machining? They are Rigidity, Rigidity and Rigidity.

Your setup looks floppy.

Mount your big lathe chuck on the main HBM spindle. Stick your toolpost to the table. Then you can swing your wheel.

yeah I agree with you, our setup is still a bit too floppy, mostly because the faceplate is 0.5" and it bends slightly as we try and cut, biggest issue is to have the rim dialed in just right.
We can't mount our large chuck to HBM the spindle is way too small for it

 

[Donkey Hotey]

Do you have 3 or 4 Kurt 6" vises? Mount the vises to the face plate, with soft jaws only on the moving jaw (no fixed jaw). Add an appropriate rim-grabber profile cut into each soft jaw. It would create a giant four-jaw chuck out of the plate and vises. The vises might give you some added stiffness. The travel range of the vises is probably enough to grip a large range of rim diameters.

(might be too heavy for that setup but, might work in a different one)

 

[Garwood]

yeah I agree with you, our setup is still a bit too floppy, mostly because the faceplate is 0.5" and it bends slightly as we try and cut, biggest issue is to have the rim dialed in just right.
We can't mount our large chuck to HBM the spindle is way too small for it

What is outboard of the quill on your hbm? You should have a primary spindle flange there with a bolt pattern in it right?

Mount your chuck to that, not the quill.

 

[???]

Those threaded rods are like tuning forks and will probably not help with the vibration that they feed back. Different cutter would help also, looks like a inserted face mill type cutter which is probably not helping. Its a Sunday and the lathe is warming up, I'll model a mock up of what I would do and post it. I do like the redneck engineering setup, just needs a little improvement.

 

[???]

Use C channel to fabricate risers, you can box or triangulate them, or weld in ribs. Plates top and bottom. Top side tapped for clamps. Use existing plate which does look a little thin to attach them to. Excuse the colours.

 

[EmGo]

Right idea, just needs beefier. Knock out a ring, decent thickness not some feasily-ass thing, steel not aluminum, with a step so it will fit loosely around the rim. That's just to make it easier to hold while you bolt everything together, not do any serious locating.

Put holes in it (more is better but looks like you only have four t-slots) then use heavy studs to the table, not like your feeble 3/8" allthread but at least 1/2", or better yet 5/8" like the long coupling studs that come with a set of bridgeport holddowns.

Clamp them buggers down to the table hard and it'll put the kibosh on your vibrations. It's the right idea but you can't get enough grip or pull with those shrimpy little clamps and pissy pullstuds.

 

[Garwood]

I don't think that setup with the rotab is going to fly period.

There's too much floppy shit going on there then trying to chew a torch cut weld off with a big cutter hung out on a baby quill.

If you want to do this with the wheel stationary you need a real HBM angle plate- The 500 lb variety. Lock it down with 3/4" or 1" studs. Then use a facing slide with a big bar (not a little criterion thing, a real 1500 lb hbm facing slide) or make a boring ring and use a HD boring cartridge like a 1" or 1-1/4" shank Devlieg.

I figured he probably doesn't have a big boy angle plate or he'd be using it and facing slide is pretty unlikely as well. That's why I recommend big chuck on the spindle.

HBM's make pretty good giant lathes as long as you don't fuck up and turn the wrong lever.

 

[Ox]

Use C channel to fabricate risers, you can box or triangulate them, or weld in ribs. Plates top and bottom. Top side tapped for clamps. Use existing plate which does look a little thin to attach them to. Excuse the colours.View attachment 408140

I will see your design, and raise you 4 tie bars.
No reason in this app (I don't think) that a tie bar between adjacent towers wouldn't work, and that would tighten that set-up up immensely!

Same for his set-up already. Just tieing that together would doo wonders.


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Think Snow Eh!
Ox

 

[Ox]

Other improvements to the original set-up would be:

1) Just toss some cardboard under it to help keep vibration in check.

2) Add something down below.

A) This could be at min, just a block that get's ponied up to the rim edge and tightened down to make sure that the rim doesn't have a chance to walk.

B) A toe type clamp may be an upgrade to (A). Maybe.
If you don't feel that you can tighten it down enough to keep from sliding during chatter, then maybe not, but I would think that you could. Just may need to make sure that the working edge of your clamps are well radiused so that you don't dig into the sealing surface of the rim. (or bend it)


Here is an example:

See the blocks that I have around this part?
I have the part blocked in tight, and then pulled down too.
But also, by tieing your clamps together, you will get it pulled down better.
Also note that my studs are not threaded into the block, they are into the T-nut.
The jam nut on top of the perimeter blocks is a 3rd and 4th hold down for the block!

On the HMC tho - I have used 1' tall blocks to support clamps.
But keep in mind that 1/2 (for arguements sake) of your clamp force is going into your step block, and half into your part. On a tie-bar set-up like this, you can really giv'er!






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I am Ox and I approve this post!

 

[Garwood]

Going along with what OX is saying- When you're doing stuff like this and trying to make a "found art" setup that gets the job done the best thing you can do is put your hand on all the various parts of your setup while you try a cut and if you feel vibration, add stiffening and/or dampening devices until the vibrations stop.

 

[Ox]

Going along with what OX is saying- When you're doing stuff like this and trying to make a "found art" setup that gets the job done the best thing you can do is put your hand on all the various parts of your setup while you try a cut and if you feel vibration, add stiffening and/or dampening devices until the vibrations stop.

I have used a 16# sledge as a vibe damper already.
Just hold it up agginst the offending object.


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Think Snow Eh!
Ox

 

[plastikdreams]

You can get some pretty strong destaco clamps, we use them to hold superalloy castings while they are machined in 3 4 and 5 axis machines.

 

[MicroMach]

BAM!

we still need to add a support at the top with two wheels around the big plate , there is a tiny vibration at some spots but overall our setup works great for our needs