Thread: Metal to Wood !

This may help. The blue ball is with the tool at right angles, the green ball is at ~45 degrees (I have shown all quadrant positions). With the same circle, the ball is larger, but still a ball

Might drill some more holes in mine at the base, so I can use 45 degrees

Cheers

Originally Posted by gawdelpus

Hi Tim I am probably missing something here, the mechanics of turning a ball dictates that the pivot point is at the centre of the ball and the cutting tool is square to that pivot ,so when pivoted backwards and forwards it arcs across the centre point of the ball. to form the size required . Any tool advancement has to remain in this geometry. If the tool is placed at an angle ,then a different means of advancing the tool needs to be accommodated ,eg the tool remains fixed relative to the centre of the ball, and the tool holder has to advance as a unit , As any adjustment of the tool inwards to reduce diameter would shift the tool away from the centre line ? Keen to see any sketch or pictures of what you are saying as I just don't quite get it . Cheers ~ John

G'day John

I've no idea about the maths involved in this.

I'll let someone much smarter than me explain that.

I have made many balls with my Vermec Ball Cutter and only found out about using an offset by trial and error.

" quote"
John. The cutter still works on the centre line but because you are only cutting half the ball you can have the cutter advanced a little on the headstock side and go past the centre on the free end. The "swinging" arm still moves in the same arc.



please!! there you go again agreeing with me!! Please stop!!! keep it up and I'll start thinking I'm an expert.

Cheers

Tim

Originally Posted by dai sensei

Might drill some more holes in mine at the base, so I can use 45 degrees

Cheers

Neil

I think from memory, 45 degrees will be too much.

I would suggest one bolt in the centre of the post will allow you to experiment with the amount of offset.

Cheers

Tim

You could be right Tim. I'll think a bit more about it, only using a M8 HT bolts at present, a larger bolt will have insufficient edge distance to the existing holes. I could always fill the existing holes I guess.

Bugger ! should have grabbed one of Neils round carbide tools while I had a chance lol. Now I will have to redesign my turning tool to allow for an offset hehe , ah well no biggie
thanks for the feedback gents~ Cheers ~ John

still got one spare, I'll add it to your bill

I found when designing the sphere attachment for my lathe it was better to have all the contact surfaces inline with the pivot.Introducing offsets can cause chatter if the structure is not rigid enough. The large spheres I make are roughed with a scraper and then sometimes finished with carbide tips made for aluminum. I also found that if the cutter is able to be rotated, it can be pulled across the surface with the tip (triangular cutter) trailing (cutting with the side) so to cause a slicing cut that is very smooth as a finish. The cutters for aluim have a deeper groove for chip breaking so are much smoother for wood. The round cutters are also good. I use the highest speed I can for the finish cut.

Originally Posted by David Pride

I found when designing the sphere attachment for my lathe it was better to have all the contact surfaces inline with the pivot.Introducing offsets can cause chatter if the structure is not rigid enough. The large spheres I make are roughed with a scraper and then sometimes finished with carbide tips made for aluminum. I also found that if the cutter is able to be rotated, it can be pulled across the surface with the tip (triangular cutter) trailing (cutting with the side) so to cause a slicing cut that is very smooth as a finish. The cutters for aluim have a deeper groove for chip breaking so are much smoother for wood. The round cutters are also good. I use the highest speed I can for the finish cut.

I agree with David about the chip breaker.
In softer timbers, it will cut much cleaner than a flat top cutter.
A 16mm round flat top cutter will expose more cutting edge to the wood. This can load up the cutting edge and lead to chatter when working around towards the stub.
A 10 mm round tip with a chip breaker is the way go.
David, I was interested in your use of a triangular cutter.
Good thinking an your part.
Cheers

Tim

Hi Neil,

Yep I will definitely get one of those Vermec models when I get the lathe up and running again - got a new 3hp motor for it this week.

I would like to try it with the oval turner too - should make for some interesting pepper and salt grinders.

Cheers mate

Ok here is mine, still with a double bolt system to attach the main tool post to the swivel plate, painted with hammer-tone blue. The top tool clamp has a brass insert to ensure the SS tool is not damaged when clamped. I will drill and tap a central hole in the tool post to have the option of a single bolt in the middle. It will raise the cutter edge slightly, but if a problem, I have a plastic slide under the tool post that can be removed lowering the post.

I made mine so it would fit both the smaller WoodFast, plus my larger JET. When I use the JET, there is a spacer block for the tool post plus a ring plate to attach to the bearing housing base, to allow for the larger ball capacity and ensure the jig remains central to the lathe respectively.

The main cutter is a 8mm round timber cutter from the WoodCut systems I had spare. I have slanted the cutter at 15 degrees similar to the Vermec system as I have found this to give a better finish. The ball shown is a dry old piece of Blackwood, with literally no tear-out, so I'm pretty happy. I too rough out the ball with my normal chisels.

Cheers

Slicko!

Originally Posted by dai sensei

Ok here is mine, ............

What have you got in the corners of the base plate that sits on the bed Neil? Can't figure it from the pic

The way this locks onto the bed is with a 16 mm stainless stud locked into the bottom of the bearing housing , the 4 corners have a hole drilled to take an 8 mm shaft to lock the housing onto the bed ,less sophisticated than a camlock ,but very effective , the plate underneath is tapped to take the 16mm stud cheers ~ John

Originally Posted by TTIT

What have you got in the corners of the base plate that sits on the bed Neil? Can't figure it from the pic

There is an 8mm hole in each corner for a rod I use to tighten the bearing housing down to the lathe. The bottom plate (under the lathe top plate) is threaded and the bearing housing has a threaded rod, so I twist the housing to tighten by hand, then the rod to fully tighten. This is in lieu of a cam lock, which would be better, but takes up more room out of the available height.