Parting off help!

Edited By Frances IoM on 02/09/2021 19:32:59

William, you have a lathe just make a longer stud. As for the chuck, surely you can see how it's held on, from Warco's own website it has a flange mounting so no problem running in reverse?

Tony

Considering I have never cut a thread on this lathe, this will be a task in itself

I am not at the lathe at the mo - any idea what size thread is in the compound slide for the tool posts? The parts manual just calls it a 'stud'.

I have a Warco 250 and had issues with parting off until I made a solid tooltpost that replaced the original. When you look at the construction of the tool post and compound slide it has very little rigidity especially when parting off larger diameter stock. Even with my new tool post I have to make sure everything is locked down. I use a 2mm wide HSS parting tool.

I based my design on this toolpost.

This is the page address if above link doesn't function.

https://journeymans-workshop.uk/wm250qctp1.php

I see the article involves sacrificing the compound slide complete, with its entire functionality, in order to fit a QCTP. It might reflect the sort of stuff I make, but myself, I'd never do that.

I use a WM250V with bog-standard 4-way toolpost and compound slide - as indeed appears in use in some of the photos in the article . I even use the same partoff tool that appears in photo 11, and so far haven't met insuperable problems parting anything less than 2" EN8 bored bearings, which shrieked like banshees until I ran away and found a bandsaw I could use.

Edited By Mick B1 on 03/09/2021 13:07:41

Apologies in advance if I come across as a little sharp but we have been through all this so many times. There is plenty of parting off advice on this forum already so I won't repeat mine. However, I will revert to something I have said time and again that sometimes you just have to use common sense and you will find you know more than you ever thought you did. You don't have to ask about the lengths of a stud or the thread, just make it to fit with what you have to hand. You just have to look at the job. If you can't cut a thread buying a die would be the answer. Is it because traditional skills are no longer taught in schools or that people have just become used to being told every single detail of exactly what to do? Like the majority of people on here, I would suggest, I have tackled and succeeded at tasks that I have never done before simply by standing back, assessing the situation and applying good old logic and common sense. We all have to check things and information at some point, I grant you, but I see such elementary questions asked sometimes it almost beggars belief. Don't get me wrong, I am willing to help anyone who is genuinely in need, within my knowledge and skills, but only after they have exhausted all their resources themselves and don't expect me to do their homework for them because they will learn nothing.

Edited By Chris Crew on 03/09/2021 14:38:24

Chris Crew

Roy

Chris fully understood, I am a school teacher in a Primary School, I teach computing and have built a MakerSpace for developing digital and physical making skills and to give the children an insight into things they won’t normally do until they are in Secondary School.

This lathe is in the MakerSpace.

While running a couple of simple building projects this year I saw how much the children’s ability to take an idea and make something have degraded even compared to a few years ago.

Oh by the way, I wasn’t asking for the length of the stud, I was asking if anyone knew the thread size off hand as I was going to order a Die. Turned out to be 10mm and I had some 10mm threaded bar which I have used as a temporary measure until I can turn a proper stud.

P.S. I usually ask questions because I tend to over think things.

If you have a M10 Die,(and presumably a Die Holder ) you need a length of 10 mm diameter steel bar.

Adjust the Die, using the M10 studding as a gauge, very slightly tight probably.

Use plenty of lubricant (Ideally Trefolex or Rocol RTD ) and cut the length of thread that you need on each end of the bar, once it has been cut to length. At a pinch use grease or oil, even Bacon fat can suffice

Use the lathe, chamfer the end of the embryo stud, and the job will be so much easier and more accurate than trying to cut the thread by hand. (Less risk of drunken threads )

If you do the job under power, I would suggest minimum speed in back gear. Otherwise rotate the chuck by hand, or by means of a Mandrel Handle.

Don't overthink things, remember the radio ham's motto: KISS - Keep It Simple Stupid. Often the simple method is the easiest, using practice rather than high grade theory.

The only worry about the coefficient of friction is whether the nlathe or you have enough grunt to produce what you need.

Howard.

With regard to chatter, if it chatters, and the tool geometry is right, and set on, NOT above, centre height, reduce the speed.

It sounds as if you will not be able to make and fit a rear toolpost.

However, with a flange mounted chuck, you can safely run in reverse., with the parting tool mounted inverted in the front toolpost.

I do not use any top rake, leaving the HSS blade as is, just grinding a clearance on the front, and ensuring that the cutting edge is not, in the case of an inverted blade in the front toolpost, below the centreline. (So that the blade cuts, but does not rub ) having an inverted blade above centreline will encourage the work to try to climb over the tool, probably to the detriment of both.. Again an argument for maximising rigidity and setting the cutting edge on centre height.

Apart from weakening the cutting edge, and reducing the area to conduct away heat, a lot of top rake will encourage the tool to wear or dig in, hence my preference for Zero top rake.

Lubrication will always improve matters. I have rigged up a gravity feed, with a valve to control the flow to a jet mounted on a small magnetic base on the Cross Slide. The reservoir is just a plastic soap dispenser bottle, with a piece of plastic windscreen washer tube rammed onto the spout of the pump, and sited on a shelf above the lathe. Nothing fancy there! Crude but effective.

If you use blades either with a groove on the top, or T section blades, jams are less likely, since the swarf is narrower than the groove being cut..

HTH

Howard

Edited By Howard Lewis on 03/09/2021 17:56:54

What I like about the forum is it's willingness to answer questions - enormously valuable when I was a raw beginner, less now I'm no longer a virgo, but I'm still learning new tricks.

The forum isn't an organised reference source like Wikipedia, and it doesn't have a first class search either. It has a Question and Answer format, which can be repetitive. Inevitably the same subjects come up again and again. I don't mind - helping people get started by answering their questions keeps the hobby alive! Newbies arrive on the forum, are educated, and move on to greater things.

Sad state of affairs if a primary school teacher like William told new classes to use their common sense just because he was fed up teaching the same material year after year! William may get bored repeating himself, but his job benefits different children every time. Although a river looks much same day by day as it rolls to the sea, the water is different: just like life.

By the by I strongly suggest there's no such thing as common sense. Everything has to be learned...

Dave

Common sense was used here to mean something I learnt(or was taught, they're not the same) so long ago I've forgotten how ignorant I was.

I think the point of the article has been a tad missed. The idea of making the cross-slide toolpost was to enable turning the compound slide to remove the cast in boss. Perhaps *** Page 2 *** makes thing clearer.

Once finished as described the top-slide can be re-fixed but you end up with an extra bit of interchangeability:-

• A cross-slide toolpost using the 4-way or QCTP
• A top-slide toolpost using 4-way or QCTP
• A rear toolpost using 4-way or QCTP

The modification would needs re-working to fit the WM180 though and of course fitting a QCTP is unlikely to improve rigidity for parting off.

John

Edited By Journeyman on 04/09/2021 08:21:15

IF you can make and fit a rear toolpost, I would urge you so to do.

I made one for my ML7 and never looked back.

When i got my larger lathe, I made a four way rear toolpost. This allows work to be Front, or Back chamfered as well as parted off, leaving the last op to be just a skim to clean up to length.

Pity that I have yet to find a means of fitting one to the original Cross Slide on the mini lathe!

Might be worth doing a bit of drilling and tapping to extend the Cross Slide (although it would then reduce the travel by fouling the splash back. Thinking cap on!

Howard

Edited By Howard Lewis on 04/09/2021 17:32:12

Quick one on inverting a parting off tool. I have a 250 series QCTP (Which I need to modify to fit correct and I will go back and update one of my other threads to sort that out).

I have bought a T Shaped Blade from Chronos Here is an image of the bladed mounted in it's holder.

To invert it, can I simply turn this one upside down, like so?

IF you are going to mount it in the front toolpost and run the lathe in reverse, yes., as long as inversion does not cant the tool over from the vertical.

The tool holder already provides top rake, so don't grind any on the tool, just front clearance, and set on the centre height.

Since you will be changing tools easily (The purpose of a QCTP ) it may be worth making a Centre Height gauge with two blades. The upper one will be for tools mounted normal way up, which touch the underside of the blade, and the lower one for inverted tools, such as your parting tool, which will just touch the upper surface of the lower blade.

Have a look at my albums.

Either that, or spend time experimenting with, and adjusting, every tool, facing the end of a bar until there is no central pip. But you may still need a gauge for setting boring tools.

Howard