Machining a radius

[peterhodParticipant @peterhod]

Hi

I have a wheeling machine (English wheel). The wheels are 8″ top 2″ bottom.

I want to radius the edges of the wheels to soften the edge so the edges don’t leave lines.

I can’t use a ball turning attachment as the wheels are to big. I could grind a form tool out of H.s.s but that won’t work on the upper wheel as it is ground and hardened and anyway I want a nice radius!

I can’t seem to find any carbide tools with suitable inserts. I did find one tool but £212+vat is a bit outside my budget!

 

I would ideally like to buy something off the shelf. Any advice?

 

Thanks

 

Peter

[JasonBModerator @jasonb]

Grind the form tool from carbide not HSS

May work holding a TCT router bit in the toolpost and use that as your form tool, Though I have only done that on unhardened steel.

Work out a set of co-ordinates to machine the curve in a series of steps with a carbide insert and then use abrasive to blend the resulting stepped surface smooth

[Martin ConnellyParticipant @martinconnelly55370]

Anyone local to you with a CNC lathe that can help?

Martin C

[Martin KyteParticipant @martinkyte99762]

Hand turn them

[duncan webster 1Participant @duncanwebster1]

What Jason said, but I’d take off the steps with a file. Just make sure you have a good handle on it. Single cut file for preference.

[JasonB]

On JasonB Said:

Grind the form tool from carbide not HSS

May work holding a TCT router bit in the toolpost and use that as your form tool, Though I have only done that on unhardened steel.

Work out a set of co-ordinates to machine the curve in a series of steps with a carbide insert and then use abrasive to blend the resulting stepped surface smooth

A combination of several of these might do the trick. I think my DRO does stepped curves. Also liking the router bit idea. Using a file on the lathe is a no no for me. I used to do it but was careless one day and picked up some bruising and cuts on my hands. Luckily nothing more. I keep the guard down nowadays.

 

One way might be to mill the edges on a rotary table. with a suitable cutter. I’ll look what cutters might be available.

 

Thanks to all

 

Pete

[bernard towersParticipant @bernardtowers37738]

If you fix a radius point to the bed of the lathe  and have a pivot against the crosslide you will get a radius equal to the length of the pivot rod as you feed the tool across the workpiece

[old martParticipant @oldmart]

Unless you have a large DSG lathe, it would be extremely difficult to turn the rads on a hardened wheel. I would use one of my 10″ diamond files and a low speed in the lathe, say under 100rpm and gently form a small radius. Then the surface would need finishing with progressively finer wet and dry paper, with the lathe suitably covered to keep any abrasive dust off it. A machine shop with a cylindrical grinder would be able to do it for you if there is one handy. The large wheel should be plenty wide enough when used with the smaller rounded profile wheels to not allow the work to come near the corners.

[bernard towersParticipant @bernardtowers37738]

Sorry Old Mart thats a right faff and would not be a measurable rad just do it properly it doesn’t take that long and the tools are there for the next time

[howardbParticipant @howardb]

If I was doing this job professionally for beer tokens+ vat what I would do is:-

Chuck the 8″ diameter upper wheel in the lathe and set it up dead  true, if necessary in a four jaw chuck.

Set the spindle speed something like 200 to 250 rpm – forward rotation.

The 8″wheel is described as hardened,  however, you do not know how hard, or whether it is case hardened or through hardened.

To me, that rules out carbide radius tools, you don’t know what you are up against.

If it digs in or chatters you are bust.

I would procure some 125 mm flap discs for your angle grinder in fine grit size more than 300 grit and gently work the radius round with these discs, with the work turning at the 200-300 rpm referring to a radius gauge.

The images of these 8″ wheels from USA sites seem to suggest that the edge radius is about an 1/8″.

The finer the disc the less it will take off in a pass so less chance of a f*** up.

Finish off with fine emery or wet and dry paper + oil wrapped around a wooden stick, not a file, if it slips it might gouge the work piece.

Just my two pennyworth !!

 

[JasonBModerator @jasonb]

If your DRO does indeed have the ARC or radius function then it’s almost a no brainer to use that. This is the type of curve you can cut with that function, just needs a very small amount of final finishing. Would be even smoother if done with an insert rather than this that was done with a standard milling cutter with no effective “tip radius” That is a 1/2″ cutter for an idea of size

[old mart]

On old mart Said:

Unless you have a large DSG lathe, it would be extremely difficult to turn the rads on a hardened wheel.

200 rpm for an 8″ wheel and a CBN insert with about three thou depth of cut. You’ll end up with a mirror finish!

[Dave HalfordParticipant @davehalford22513]

Forgive me, I thought the big wheel stays flat and the small barrel shaped wheel was changed to suit the curve required????

The edges shouldn’t touch the work at all given the two wheels only meet in the very centre of each wheel.

[peterhodParticipant @peterhod]

Thanks for all your advice.

It’s not 100% necessary to do this. I bought a Chinese English wheel. I chose this one because it had a bigger top wheel, most have wheels that are to small. Apart from the wheels, the rest of it was a catastrophe unbelievably badly made. The worst Chinese equipment I have ever encountered. I have re-manufactured it and it now works great! It’s so good that I want the last little bit of performance by rounding the wheel edges.

 

I’ll let you know how I get on!

 

Peter

 

[Dave Halford]

On Dave Halford Said:

Forgive me, I thought the big wheel stays flat and the small barrel shaped wheel was changed to suit the curve required????

The edges shouldn’t touch the work at all given the two wheels only meet in the very centre of each wheel.

Hi, you are correct. However when the edges of the wheels are sharp they can put lines in the metal. You can wheel out the lines but better if they weren’t there in the first place. On traditional wheels they are square edged but there is a trend now to soften the edges. Every mark you put into the metal has to be gotten out.

 

Peter

[JasonBModerator @jasonb]

Should have got a Ranalah😊

[JasonB]

On JasonB Said:

Should have got a Ranalah😊

Outside my budget and space!

[Dave Halford]

On Dave Halford Said:

Forgive me, I thought the big wheel stays flat and the small barrel shaped wheel was changed to suit the curve required????

The edges shouldn’t touch the work at all given the two wheels only meet in the very centre of each wheel.

That’s exactly what I said earlier, but was ignored.

[JasonBModerator @jasonb]

Depends on the profile of the bottom wheel. You can get flat ones. Even the alterations he mentions will still leave most of the bottom wheel flat

[old mart]

On old mart Said:

On Dave Halford Said:

Forgive me, I thought the big wheel stays flat and the small barrel shaped wheel was changed to suit the curve required????

The edges shouldn’t touch the work at all given the two wheels only meet in the very centre of each wheel.

That’s exactly what I said earlier, but was ignored.

I’m sorry if you think you were ignored. That’s not the case. In a theory the edges shouldn’t touch the work piece. However in practice sometimes you pull up on the metal particularly when you are using the flatter wheels and are near a fold. Likewise sometimes the the lower wheel can wander a bit to far where the radius of the lower wheel is less than the radius on the metal. In this case you will get a line where the sharp edge of the wheel digs into the metal. These lines are quite hard to get out without raising the surrounding metal. It’s mostly operator error that causes the lines.

If you look at the Ranalah English wheel you will see that the edges of the wheels are radiused. When you look at some of the very good people like Covell on Youtube their wheel edges are radiused as well.

Thanks for your input.

[Neil LickfoldParticipant @neillickfold44316]

A tool post grinder will cut the wheel. Many options, but just a series of flats, and then blend those until a full radius. With a free cad , draw the radius and then look at the angle created and how long that flat is.  Set in progressive flats. Tedious but does work. So effectively create the radius by a lot of chord cuts.

You can get ceramic inserts that will cut the roller if it is really hard, or anything over 48Rc hardness. At 46 Rc hardness then buy a Hard turning carbide insert, like Seco grade TH1000, or Mitsubishi grades VP05RT or MP9005, these will cut steel to 60Rc no problem at around 30 to 55 m/min surface speed depending on cut depth. A ceramic like the Kyocera PT600M with coolant will cut at 220m/min and about 2 thou per rev feedrate with a 0.2-0.25mm(8 to 10  thou depth of cut, depending on the HP of the lathe you are using.

Neil

[peterhodParticipant @peterhod]

I was hoping that one of you guys would have a simple solution! Most of the above I have done in the past.

 

My lathe is a Warco GH1327 and is surprisingly sturdy. I can part off 3″ steel with the power feed. I will probably grind a carbide tool to the profile and have a practice on some 3 inch bar. Simple is usually the best approach.

Here is the wheeling machine. I had to make all new spindles for the lower anvils as they were all out of true. The lower adjusting piston was crazy sloppy and the bores of the top and the sliding lower (if you get my meaning) so I made a new piston stepped to fix the problem. The threaded adjuster was very sloppy and bent so I replaced it with a new adjuster and added a ball bearing thrust bearing to the adjuster below the piston. It runs very smoothly now.

There is some flex when you tension it but not terrible. It works quite well although the lower anvils may be a little small.

 

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