Turning 10x2 Mild Steel Spacers

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faavs730222

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Hi, I bought four 10 x 2 inch circular mild steel stock from our local engineering shop. The idea is to turn 4 wheel spacers for my Series Land Rover, to increase the wheel offset. The engineering shop cut it into circular shapes and I asked them to drill a 1'' hole in the center. I want to fix the stock to a 1'' shaft to turn the stock.

I have a Knuth 3Hp lathe with a 14" swing and 1m between centers. I never machined a plate so heavy.

My question: Can my Lathe handle a plate so heavy?
At what RPM should I cut?
Would it be safe to fix the plate to a 1'' shaft to machine the diameter?
When I have the correct outside diameter, I must increase the inside diameter to about 4". Should I fix the
plate in the 4 Jaw chuck to do that?

I would appreciate any comment.

Thank you,

Anton
 
Their should be a spec some ware for your spindle bearings load capacity, it sounds like a fairly big lathe so it should be fine.

Mounting on the 1" bar probably depends on how your intending to do that :) might be worth posting a sketch of what your thinking.

The speed chart on my lathe recons 25rpm for 10" diameter mild steel using HSS tools.

Stuart
 
Your steel "washers" should weigh about 20kg each. A 14" lathe should be able to handle that.
RPM is not really applicable, you want Surface Feet per Minute. Mild steel runs at about 100 SFM. So at 10" dia, (or 2' 8" circumference), then 38 RPM = 100 SFM. However thats also a lot of mass so err on the slow side to allow for unbalance.
How did you plan on fixing to the 1" shaft. Personally I would get the shop to cut close to the 4" ID hole and grip that with your 4 jaw Turn the OD to size then reset and bore the ID out to dimension. Thats a lot of material you wont have to remove yourself.

Cheers Phil
 
I should think a 1" hole would be more than enough for a mandrel to hold that for turning the OD. You don't need to take monster cuts. I've done this, albeit on a smaller scale and what worked for me is to turn a mandrel, thread cut the tip for a nut and make flanges that go on each side of the work piece to increase the contact area. I try to make the flanges about 1/3 the diameter of the work piece but I use whatever stock I have that's close. Whenever possible, I also use tailstock support on the mandrel as well. Just centerdrill the mandrel and slip the live center in place. Give it try - works good.

As far as RPM goes, if we use the typical SFM X 3.82 / Dia., we get 382 rpm. A bit too fast, maybe but the next step down in speed that your lathe can run should do it. Take light cuts until you get it round and then you can increase depth of cut as long as the flanges hold the wheel solidly.

Then chuck it in the lathe and bore the center hole. I suspect the tolerances for a wheel spacer will be fairly generous so a 3 JC would probably be okay to hold it for boring.
 
Would it be safe to fix the plate to a 1'' shaft to machine the diameter?

I would appreciate any comment.

Thank you,

Anton[/QUOTE]

Can my Lathe handle a plate so heavy? Yes

At what RPM should I cut? Whatever speed works for your choice of tooling and machine.

Would it be safe to fix the plate to a 1'' shaft to machine the diameter? Yes but it would be a silly thing to do and take forever.

When I have the correct outside diameter, I must increase the inside diameter to about 4". Should I fix the
plate in the 4 Jaw chuck to do that? Yes

Next time have them burn the plate to within 1/4" (6 MM) of finished diameter this will make short work of such a job, starting at 1" ID and boring to 4" is absurd and will require a good deal of time.
At .100" depth of cut (.200" diameter) it is 15 passes, at. At 1" bore size begin at 1000- 1500+ RPMS if using carbide inserted tooling, as the diameter increases slow it down, at 4" 350-500 RPMS. Run the DOC and Feed rate hard enough to break the chip otherwise they will cause problems. If a high surface finish is required leave .025" on the bore then switch to a finish tool. Flood coolant as well, this will help with the chips.

Remember that you are turning, 4" OD X 2" = 25 CI - 1.5 CI of the hole or 23.5 CI of steel X 4 parts into chips, steel has a density of roughly .283 pounds per cubic inch, or 26 Lbs of chips.

Good luck
 
Last edited:
mikey said:
I should think a 1" hole would be more than enough for a mandrel to hold that for turning the OD. You don't need to take monster cuts. I've done this, albeit on a smaller scale and what worked for me is to turn a mandrel, thread cut the tip for a nut and make flanges that go on each side of the work piece to increase the contact area. I try to make the flanges about 1/3 the diameter of the work piece but I use whatever stock I have that's close. Whenever possible, I also use tailstock support on the mandrel as well. Just centerdrill the mandrel and slip the live center in place. Give it try - works good.

As far as RPM goes, if we use the typical SFM X 3.82 / Dia., we get 382 rpm. A bit too fast, maybe but the next step down in speed that your lathe can run should do it. Take light cuts until you get it round and then you can increase depth of cut as long as the flanges hold the wheel solidly.

Then chuck it in the lathe and bore the center hole. I suspect the tolerances for a wheel spacer will be fairly generous so a 3 JC would probably be okay to hold it for boring.
Click to expand...
Mike, check your math. You are off by a factor of 10, move your decimal place to where it says 38.2 rpm... Not trying to get after you, Mike, just trying to help the OP and perhaps save him from burning up some tools...
 
I would chuck it in a 4 jaw and drill with the largest drill I have then bore the id first. Then Id chuck it and turn the OD.
 
Instead of having them drill a hole, I'd burn a bigger hole myself and chuck the id, finish the OD and one face, then flip the part over and finish the bore and the other face. That is, if the faces needed finishing. Same with the OD and ID....if a burned finish is ok, then leave it alone. Why make work?

And no, there will not be a problem with that size workpiece on your lathe.
 
Bob Korves said:
Mike, check your math. You are off by a factor of 10, move your decimal place to where it says 38.2 rpm... Not trying to get after you, Mike, just trying to help the OP and perhaps save him from burning up some tools...
Click to expand...

Yup, forgot the decimal - should be 38.2. Sorry, OP.
 
THANK YOU VERY MUCH!! This is very good advice all. Like Henry Ford said, you don't have to know everything, you just have to know who to ask.
My Idea was to turn a 1'' mandrel and fix the plate on both sides with lock nuts, and fix the live center on the free side.
I will turn to you again later in the project, when I have it to size I have to start drilling the holes for the wheel studs, an I don't have a Rotary Table. I have a milling machine and a small (Hobby Size) drill press. I think I will drill the holes with the milling Machine? I am not going to take to much of the thickness of the plate, so the holes I have to drill would be a bit less than 2" deep, about 18mm (not sure how many inches) in diameter. I have to drill 5 x holes for the hub studs, and 5 holes to press in new studs for the wheel.
 
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