PDA

View Full Version : Newbie setup question?



harley2003rkc
03-22-2007, 10:02 PM
This is probably old hat for most of you. How do I clamp work to a back plate? I have never turned anything on the back plate I have and now I need to bore an 1 1/2" wide hole in a piece of 1/2" x 3" x 5" aluminum. I don't have a four jaw handy yet, and I'm still trying to acquire a mill. So I'm stuck with finding a way to do this on my lathe. For reference I'm working on a 18" x 60" engine lathe. I do have a large back plate capable of holding the work piece, I just don't know what is usually used for clamping to the back plate.

Thanks in advance.

Scatterplot
03-22-2007, 10:35 PM
As far as I know, back plates are used for driving lathe dogs and boogering up to make fixtures. I would start cutting some holes in it to bolt down some stuff, or just use existing holes/slits and use bolts with washers. Then again the total value of my shop is less than like 4 grand in HF stuff (it's got a bunch of stuff, just not nice stuff :))

That's just what I've gathered though- I've never even used the backplate on my little 9x20.

wierdscience
03-22-2007, 11:28 PM
The odd collection of bolts,tie straps and toggle bars,same sort of things you use on a mill table.Just be aware that a setup with a radical offsets might need some counterweights added to the lite side for better balance.It's amazing sometimes how little it takes to get 4,000lbs of iron to shimmy.

dicks42000
03-23-2007, 04:55 AM
OK, it sounds like we have a bit of difference in terminology first. I assumed a back (ing) plate was for mounting a chuck onto. Work is sometimes done on a faceplate....
Faceplates are probably one of the oldest work-holding methods. Check out any of the common lathe-work books, (How to Run a Lathe, the Atlas book, Sparey's "The Amatures Lathe" etc. or best of all Tubal Cain's "Work Holding in the Lathe") Lots of ideas, solutions in them. No doubt somebody, somewhere, maybe even on here, has done what you want to do.
As for setting up & securing, use bolts or studs & T nuts that fit the slots in the plate. Ready-rod (all-thread) works. As for packing/parallels, I have used ball bearing races (over the rod/bolt used to secure the work) as they seem safer than parallels or other packing that might fly out. Faceplate dogs are also useful to drive the job. A layer of paper between a finished face of the job & the faceplate improves the clamping.
Are you going to have to use an angle plate or anything for a fixture ? As Weirdscience said, you might have to look at counter-weights too if the job is unbalanced.
Having a vertical mill is nice & spoils you. We tend to forget how versatile a lathe is. Faceplates & independant 4 jaw chucks can handle lots of work that requires off-set turning/boring. I've done some precise jig-work on a faceplate using parallels as references & measuring with gauge blocks....This was in a shop with no mills....(I did have my own Rockwell at home though...)
Ran a Bullard "CutMaster" VTL, which in reality is just a big, powerful faceplate & lathe stood on end.
Ironicly, now that I have 3 lathes of my own, I do most of my fun work on a little Atlas 618. That tiny faceplate doesn't have much "real estate". I've maybe used the SouthBends 'plate once in 20 yrs. Anyone know where to get a 15" faceplate for a Cardiff. Make one, I guess.
Having a mill spoils you, I guess. Hope that helps.
Rick

Mcgyver
03-23-2007, 06:25 AM
thats a big lathe, the back plate may well be capable of the some faceplate service. When i read the post i assumed you meant faceplate, if it is a back plate, bolt big piece of say 1" AL to it and you have a faceplate - just drill and tap where needed for hold downs, studs etc. once upon a time all work was done with faceplate and centres - its still the best/only way to do certain jobs

its like the others have said, there is lots flexibility of sometimes some ingenuity required. here are some shots to give you some ideas....

This is holding a cylinder head for lapping, standard set up using strap clamps. note the bearing race used a parallel. faceplate was the way to do this, had to spin the work not tool and clamping surface was the bottom (4 jaw would've worked)

http://i20.photobucket.com/albums/b201/michael0100/DSCN8953.jpg

Here's another cyl head, this time with a valve chest face that is used as the reference surface. head clamped to an angle plate bolted to faceplate. Note the 1" channel diy clamp, this is very handy material to have around for this purpose

http://i20.photobucket.com/albums/b201/michael0100/DSCN8959.jpg

Here's a largish dia split ring that needed both face and bore turned, soft soldered the blank pieces to the work and clamped them to the faceplate - yup more 1" channel clamps.

http://i20.photobucket.com/albums/b201/michael0100/TC%20Shroud/6mountedonfaceplate.jpg

Here are some other newbie faceplate comments.

1) careful torquing down the bolts. if they are supported (like where i bolted the angle plate) fine, but if not (like the strap clamp bolts) do not overnighten. you can warp the faceplate which overall is a thin section

2) keep it slow - these are not as rigid as 4 jaw work, and you don't want something letting go. its an out of balance set up so speed could literally kill. use counter weights to roughly balance if necessary (see photo 2)

take pics, and what are you making?

harley2003rkc
03-23-2007, 08:21 AM
Mcgyver, thanks I kinda thought you guys might suggest strap clamps. And yes my terminology is was wrong. I'm working with a face plate. I do have some t-nuts that properly fit it, but I'll have to get some strap clamps.
Thanks guys. I Wasn't sure if a setup like this was safe. But I'll probably try to complete this operation around a 100 rpm if possible.

JCHannum
03-23-2007, 09:40 AM
A note of caution on face plate work. While many types of hardware are useful with clamping and holding on a milling machine table, some caution should be used when applying the same to faceplates.

The milling machine table is static, but other forces become when the work is rotated at speeds encountered on lathes. It is recommended that a higher grade of fastener such as Grade 8 equivalent bolts and studs be used rather than all thread.

Failure of a fastener or setup on a milling machine usually results in damage to the workpiece or milling cutter. Failure of a fastener on a lathe at speed can launch a heavy part capable of serious injury to the operator. The caution regarding counterweights also is quite valid.

Not to be critical, but the first picture McGyver shows should be avoided at all but the very lowest of speeds. The loose risers under the step blocks potentially could come adrift at relatively low RPMs, causing the entire setup to fail. I would recommend through bolting a riser or packing to the faceplate of sufficient height to eliminate the step block.

Faceplates can be considered as consumeable tooling, and drilling and tapping holes in them to ensure that a setup is safe is never a bad idea.

harley2003rkc
03-23-2007, 03:36 PM
JCHannum, you have made a critical note about fasteners. I'm a big fan of Grade 8 hardware. I've been known to replace many a bolt with a Grade 8 from the local Midstate Nut & Bolt. When possible I restock even my home nut and bolt stock when I can catch sales.

Mcgyver
03-23-2007, 05:20 PM
A
Not to be critical, but the first picture McGyver shows should be avoided at all but the very lowest of speeds. The loose risers under the step blocks potentially could come adrift at relatively low RPMs, causing the entire setup to fail. I would recommend through bolting a riser or packing to the faceplate of sufficient height to eliminate the step block.

Faceplates can be considered as consumeable tooling, and drilling and tapping holes in them to ensure that a setup is safe is never a bad idea.



JC no issue with criticism, I can't disagree with our point. For the slow speed lapping I was doing imo the set up was fine, but agree its not best example to present to newbies. Harley or anyone else, do heed the speed warnings! If something let go at 75 rpm, the concern was a crash rather than stuff flying and given the clamp pressure there was and light loads (lapping), I felt it was safe

In general, so far as bolts go, imo Id pull hunks of cast iron out of the faceplate before I busted one of those strap clamp bolts. 1&2 use strap clamp bolts, #3 is ready rod. I wouldn't tighten one of these set up's so much that there would any danger of snapping even ready rod,.faceplates are a very light duty clamping surface compared to the milling table. I know over-tightening is a bit ambiguous, but lets say if you are in any danger of snapping a 3/8 bolt held in cast iron on this size machine, youre there :D