Member postings for Manofkent

I wonder if I could get your thoughts on sharpening and mills / slot mills.

I have a Clarkson tool and cutter grinder. I have been learning to sharpen my blunt end mills.

Some people say sharpen the end only (which is reasonably easy ...now).

But I notice my mills will normally be cutting in a horizontal plane. This suggests the bulk of the cutting is made by that small part of the fluted side next to the end.

If my observation holds water then any sharpening would need to be both end and flutes.

What do others think please?

Also can anyone advise the best angle to relieve the end cutters, not the 5 degree angle but the one the raises the cutters outside edge over the centre. I have been using 2.5 degrees, but not sure this is enough.

Many thanks

John

Thanks all for your good advice. Now I understand.

Interestingly two if my machines are already 3 phase, which I run from a rotary converter.

Looks like I shall be adding the Myford to the 3 phase list!

John

Hello.

I have a Myford lathe with a single phase motor.

I want to put a vfd speed control on it, but have struggled to find one that is just single phase. All I can find are 3 phase output ones.

Can anyone help me either to suggest what to look for, or what you are using and how successful it is?

Many thanks

John

I helped a colleague at our club make some for a 2.1/2 gauge loco. He used clock springs which can be bought at various sizes on the bay.

I got involved because I have a spark eroder which we used to bore and shape the spring steel, although others may explain how you can soften them by heating.

John

Good points all.

This has been incredibly useful - thanks to everyone.

I was thinking about screwcutting boiler fittings because i like the challenge of learning something new, and I want to master this CNC lathe.

Looking around the web I can find general inserts for whitworth threads, but the specific ones for each pitch need a bigger toolholder. I may just make the toolholder - this would be a fun thing to do on my edm machine. (Another curiosity purchase of mine).

When I can screwcut like Andrew i will be more than happy .

Ps ML10 Lathe is a metric one which limits the imperial threads I can cut .

John

Hi Hopper

For this exercise I was using a HSS ground tool like this one: https://www.chronos.ltd.uk/cgi-bin/sh000001.pl?WD=threading%20hss&PN=HSS_DOUBLE_ENDED_THREADING_TOOLS%2ehtml#a136220.

It feels like a bit of a blunt instrument really, and probably does need sharpening now.

If I have a lot of threading I think something like this would be needed: https://www.cutwel.co.uk/thread-making/indexable-threading-single-point-threading/whitworth-threading-inserts/external-right-hand-whitworth-threading-inserts

I was actually thinking I could make my boiler fittings on the lathe - ME threads 40 and 32. It is all a learning opportunity and I love learning new skills.

JohnF - I updated my profile but essentially I am in Taunton and a member of the excellent Tiverton Model Engineers club.

John

Pete - thanks for your comment. I think this may be why my previous attempts (on my ML10 lathe) seemed to end in the scrap bin. Now I know what to look out for.

Hopper - I can just about grind a HSS knife tool. Getting a Whit profile to the right angle and depth might be pushing my luck. However, you never know till you try, so would there be a profile or type of grinding wheel you would suggest to use given the small size of the tool?

Many thanks

Johm

Mick: I am afraid with the cnc machine it is a plunge in approach. Even a cut at 0.001" seemed quite big towards the end.

Jon - The machine was running at about 200 rpm - I did use coolant, but I did not take a couple of cuts at the end as you suggest (and as I remember now seeing others do).

I have identified some full form tips for 60 degree threads which came with the machine. These do look really useful. Presumably though a different size tip is needed depending on the pitch?

BTW thanks to John Gibbs for posting the thread diagram earlier. I get now why Whitworth threads are harder.

I remember a box full of thread chasers in the back of a cupboard somewhere. Next week I will see if I can lay my hands on them.

Thanks John

My thanks to everyone. Excellent advice from all of you.

I think I was probably looking for problems - when like most things it is a matter of experience (thanks Hopper).

The book is on order!

I turned the stock to 0.372"

So I wrote the program and with buttocks appropriately clenched cut to 0.04 depth at 0.001" per pass. easy to program on CNC but you have limited options to check it half way through!.

(For any Emco CNC users I used program G78 to cut the thread).

Still it seemed to work OK, except the thread was pretty "raw" on its edge, I had to be careful not to cut my hand on it!. A quick run over with a die and it was pretty perfect really.

really grateful for your help.

John

Hello. I am hoping some of you clever people out there can help me.

I am trying to learn how to cut threads in the lathe. I have an emco CNC lathe to practice on - not with any great success at the moment, and have tried to cut a 3/8" Whitworth thread with a 55 degrees tool, 16 tpi.

The puzzles are as follows:

1. If I measure a bolt of the same size it has a diameter of less than 0.375 - more like 0.360 or thereabouts. Do I start with a bar turned to exact 3/8 or do I start with a smaller bar - and if so how do I know how much smaller?

2. My biggest puzzle is how deep to cut the thread. In my reference book there is a figure h/6 = shortening, where h = angular depth of thread (whatever that is!). It looks like this could be the difference in bar diameter referred to above and ditto at the foot of the thread. So if my bar is exactly 0.375, and h is given as 0.0600, and therefore is h/6 0.01?

Do I cut to thread depth h (0.06) minus h/6 - 0.0100 - i.e 0.05? Or do I use the figure shown for depth of thread 0.0400?

3 Is there someone who can explain the difference between core diameter (0.2950) and Effective diameter 0.3350 please.

My book is "Machinery's screw thread book published in 1943!!

My apologies for these questions - I expect it is all blooming obvious - but not to me yet.!

Thanks in advance.

John

A couple of years ago I sold an L5 taper turning attachment for £200 on the bay.

Don't forget the attachment needs the splined cross slide screw as well which may be the one you have on the lathe.

Good luck

John

Hi

I bought a lovely ML10 lathe about 18 months ago, and have been hapily using it since.

It came with lots of extras - mostly Myford accessories. I am still working my way through the extras box!

Anyway - in that box were 5 tools like the picture shown.

The one shown is stamped DIAPIPT 57048.

The others are similar but most are stamped SHAW, or SHAW AUTOFLOW.

Perhaps on the large side for an ML10, the pictured tool shank is 5/8" square, and approx 7.1/2" long.

Does any of you clever people know what these are for?

Yes I have googled it but can't make head nor tail of the results!

Thanks in anticipation

John

The Tiverton Model Engineers club is nearby and would love to welcome you.

(I am a member of this excellent club).

John

I owned one for many years. It is a good and solid industrial type mill.

My only complaints were:

1. It took some effort to raise and lower the head, the handle for this being at the back of the mill, and

2. You really need the screw in taper holders. I didn't have any to start with, and the mills would drop out of the head. I made some in the end, screwcut them on my ML10 lathe- 62mm by 1.25 I think from memory.

Otherwise you have a very solid mill there.

John

I have a identical blower that I use for raising steam on my loco. (3 1/2 gauge).

I had to "strangle" the air quite a bit as it will otherwise raise a full head of steam before I get onto putting coal in the firebox!

John

Over the years I have owned and used 2 Centec 2B mills.

Neither arbor had a key, and it did not seem to be an issue in use.

I guess they were never made with a key.

John

Thanks both.

Polly models has viton balls.

Macc models looks like Nitrile only.

Advice much appreciated.

Nitrile balls are a bit cheaper. I will use them in the tender pump and axle pump.

Viton have a higher temperature rating so I will use these for clacks, snifter valve and whistle valve and hope I can keep them separate from the Nitrile ones.

John

Can anyone recommend a Uk supplier of Viton rubber balls suitable for clack valves please?

Thanks

John

William. I have sent you a PM.

John

Hi William

Well I have turned the workshop inside out, but alas can't find the plans. I have the cylinders and valve gear in one unit, some wheels and axles but that is all I am afraid.

regards

john