Mellor lathe.

[God mode restorations]

Ok so if I am seeing that right, the thrust bearing should be adjusted so that the spindle can not be pushed back. It could theoretically come forward and the gears bear on the plain bearings but really most cutting forces, certainly when turning would be pushing.

Yes. It's stumped me for a while as everything looks to be in good order. I will re assembly tomorrow and have another go.

 

[Hood]

When you have that back plate fully fitted is the thrust bearing tight?

 

[God mode restorations]

When you have that back plate fully fitted is the thrust bearing tight?

That's what I am going to check tomorrow .As it's already been spaced out it could be a fraction loose. And that could of been the problem

 

[Richard.]

It started of nice on a couple of runs.then mid way would go from a nice finish to really rough and then nice again. Very frustrating to say the least. Especially when it's difficult to pin point why

Feed rate/tool radius spencer
Your using finishing tooling with small nose rads on speeds used for rough cutting. I use the same inserts ccmt06 with 0.2/0.4 nose rads and they are lovely for 0.1mm feed per rev but for double that rate I’d guess your gonna need double the nose rad to stop it cutting that rough.
Your write up states for finer finishes you change the gear to 12T to give feed rates 2/3 as fine. Personally I’d use the rear lead screw for rough cutting with a big rad on the tool to shift the metal out then my finishing cutting Would be swapped over to the front lead screw where I can set up my own gear train with finishing tools and reduce that feed rate down for the final passes.
It would be very easy to test the theory. When you’ve addressed your spindle problem
On your next cut with the finishing inserts, get the rpm speed right up nice and fast, take a small cut and manually feed it much slower by hand. If you get a nice smooth finish you know where to address the problem. Like I say I’m far from an expert and could be way out but it’s where I’d be looking if it was mine.

 

[Richard.]

Here’s a finishing cut on a bit of scabby pipe done on my feed rates with a 0.2 nose radius finishing insert.
I’d expect set up in the same way you’ll get exactly the same. It’s a 0.2 cut off the radius.

 

[Seadog]

It started of nice on a couple of runs.then mid way would go from a nice finish to really rough and then nice again. Very frustrating to say the least. Especially when it's difficult to pin point why

It could well be the material. I've some inch hot rolled that l can never get a good finish on. It goes from nice clean sections to rough and back again.

 

[Seadog]

It may be that the spindle loaded the thrust face of the back bearing, i.e. the shimming was too tight. Is there any endfloat with everything cold? I think there should be a few thou to allow for expansion.

 

[God mode restorations]

Hi guys.
I have had it stripped right down. It's back together now. There was a little shimming needed on the thrust washer. Sorted that. Everything turns lovely and smooth. Bearings are all good. Headstock is the best it's been. It's bang on. Had the carriage off and all parts. It's all been adjusted and oiled. I am going to have a deserved brew and tool up.

 

[God mode restorations]

Lathe is running nice. Had a couple of runs. A lot better. Not brilliant but a lot more uniformed cut than yesterday . I want to make sure all headstock problems have sorted before going up a gear

 

[WorkshopChris]

Glad your sorted, what insert is that?
Keep thinking about giving them a try, at the moment am old school HSS for everything.
Got a good selection of brazed carbide roughing tools, but no inert tools.

 

[God mode restorations]

Glad your sorted, what insert is that?
Keep thinking about giving them a try, at the moment am old school HSS for everything.
Got a good selection of brazed carbide roughing tools, but no inert tools.

It's a multipurpose ccmt insert.

 

[Richard.]

Lathe is running nice. Had a couple of runs. A lot better. Not brilliant but a lot more uniformed cut than yesterday . I want to make sure all headstock problems have sorted before going up a gearView attachment 140812

Try manual feeding slower spencer see if you can improve it further.

 

[Richard.]

Glad your sorted, what insert is that?
Keep thinking about giving them a try, at the moment am old school HSS for everything.
Got a good selection of brazed carbide roughing tools, but no inert tools.

Ccmt06 or 09. It’s the ones I use.
I’ve got tools that allow all 4 corners to be used.
I buy the good ones only now as they cut so much nicer than cheap ones.

 

[Richard.]

Sometimes I do think swapping over to trianglur inserts would be better
I know the ccmt dcmt inserts have 4 corners but the angles are different making only 2 corners useful for a lot of stuff.

 

[God mode restorations]

I tried second speed. It's the same. You get a slightly better cut by hand feeding very slow.
Picture below is the best I can get it at the moment. But it's a lot better than yesterday. I did look at carriage spped but I can't reduce it even if I used the front screw .The lowest gear I can get on the front it a 30tpi thread gear and that would be probably to fast. But all in all improvements have been made. Yes it's not the finishing you guys can achieve but my machine is best part of 80 years old so can't expect miracles

 

[God mode restorations]

Try manual feeding slower spencer see if you can improve it further.

Yes. It did improve a fraction . It's getting feed rate down that's the difficult bit. Even using the front screw the biggest gear being 127

 

[God mode restorations]

Ccmt06 or 09. It’s the ones I use.
I’ve got tools that allow all 4 corners to be used.
I buy the good ones only now as they cut so much nicer than cheap ones.

I got 09 inserts. But got some 06 holders and inserts on the way to.

 

[WorkshopChris]

Ccmt06 or 09. It’s the ones I use.
I’ve got tools that allow all 4 corners to be used.
I buy the good ones only now as they cut so much nicer than cheap ones.

Will have a look at Cutwells & MSC and see what they have, i am hoping to try and get the Dean Smith & Grace home this month then i can stick it all back together and have a play.

 

[Richard.]

Will have a look at Cutwells & MSC and see what they have, i am hoping to try and get the Dean Smith & Grace home this month then i can stick it all back together and have a play.

I was buying from cutwell but tbh if you put korloy, tungaloy, sanvik into eBay you’ll find people selling boxes of them they haven’t used at a fraction of the cost.
Obviously beware there may be fakes on there so shop smart. I got a box of 10 tungaloy ccmt inserts the other day from a guy clearing out
I won them for £17.
Cutwell are good but they’ll have you for £4-£6 an insert.

 

[Richard.]

I got 09 inserts. But got some 06 holders and inserts on the way to.

The 09 will be better because the tool bars will be bigger and more rigid. Mine won’t handle a bar that big but if it would I’d buy 09’s over 06’s.