Mini Lathe Rear Tool Post

Ever had one of those days when you consider yourself a bit stupid..?..

Yesterday was a good day I machined the location tenon in the bottom of the tool post and got a really good square fit into the T slot.

Today however..? I used a centered knife tool in the qctp to mark the centre height onto the post as a guide for positioning the slot for the tool mount. I then set the post up on the mill and machined the slot, even cut the shallow dovetails...great...well no, I machined the slot on the wrong face so it is 90 degrees out.

All is not lost as I can take 3mm off the face to lose the slot and machine the correct face, what a plonker..

Edited By Ron Laden on 07/03/2019 08:46:10

Yesterday I found out why I was having so much trouble screwing a cap into a cylinder. It's because the genius I employ in my workshop had accidentally cut a Left Hand thread inside the tube. Apart from that it's a perfect match with the Right Hand thread he put on the cap.

Looking at how to recover from this boob, I found the other end of the cylinder also has an incorrect LH thread, and further that the artisan has bored the cylinder a full 2mm oversize. Seems this foolish workman can't even read his own drawings. The whole lot is scrap.

Very embarrassing. Not to put too fine a point on it, the individual in question is, it may surprise you to learn, one whom your present interlocutor is in the habit of defining by means of the perpendicular pronoun.

The whole incident will now be swept under the carpet by holding a Public Inquiry. It will conclude in 13 years time by publishing a report in 17 volumes that no-one will read...

Dave

Dave, you forgot the cost - I've been quoted £35,000 to hold a Public Inquiry for planning, I can't imaging your costs will be much less...

Despite this mornings senior moment the tool post if back on track, I have machined the tool mount with the top and bottom dovetails. I was wondering how to machine the dovetails as they are shallow (8 degrees) but it was easy in the end. After cutting the slot I angled the post in the vice and used a 60 degree dovetail cutter adjusting the post to give the correct angle.

I have offered up a parting tool (needs shortening) sitting in the mount and comparing it for centre to a tool in the qctp and it seems to be as near as damn it. Ignore the end of the blade thats how it arrived new, looks like a grinder touched the side of it.

Just waiting for an arbor and slitting saw to arrive and I can get on and get it finished.

The arbor and slitting saws arrived but having never used one any tips or advice would be greatly appreciated.

I need to cut a 1.0 mm slot 48mm long x 13mm deep, the slot breaks through into a hole running parallel along the length of the slot like a keyhole shape. The material is EN3 and wondering whats the best approach, a number of shallow passes or deeper ones or even full depth and take things slowly..?

Ron

I think Jasons milling for beginners has just answered most of the questions I had, will give it a try in the morning.

Edited By Ron Laden on 08/03/2019 21:13:07

First time using a slitting saw and it went well, well it did once I got the speed set-up.

Jason suggests in his beginners guide that you cant always go by the book speeds with small variable speed machines and that proved to be true.

I started out at 200 rpm with a 80mm x 1.0mm saw but the mill didnt like that with a couple of hesitations and a stall, increased to 250 and it was better but I could tell it was on the edge. Went up to 300 rpm and it obviously got more into the power band and worked a treat, no hesitations and it didnt feel it was working hard and cut nicely, pleased with it.

Edited By Ron Laden on 09/03/2019 09:28:18

Apart from a mounting stud and a flange nut its finished, found a M10 bolt to fix it so I could give it a try. It may be a simple post but it is very effective and so far works a treat. I havnt tried any larger diameter steel yet but parted a few pieces of 50mm alu and 25mm steel with no issues at all. It does feel different without a doubt so I assume that the rear post and the heavier cross slide have stiffened things up some what.

Certainly worth the effort in making as was the cross slide.

p.s. Forgot to say that with the tool fully forward and the cross slide back it should cut 70mm diameter, I,m happy with that as I dont fancy cutting any bigger in a mini-lathe, especially in steel.

Edited By Ron Laden on 10/03/2019 09:54:47

Ron Laden:

Congratulations on your success!

I have made a mental note of your ingenious use of a standard dovetail cutter.

The slit looks very neat - I think I cheated by using the bandsaw.

Looks good Ron and good to know the series had some useful information.

Ron,

Nice job on the cross slide and the tool post, well done. Particularly nice to see the progress you have made in a relatively short time in a modest shed, should inspire others hopefully to achieve similar. Back to the TE now?

Paul.

Ega, its thanks to you as the rear post is a basic copy of the one you showed a picture of with the tool mounted directly to the post, which is what I wanted.

Jason, I think your series is a must for beginners I have learnt such a lot from them, I look forward to them.

Paul thanks, yes its back to the engine and the little electric 0-4-0. I,ve really enjoyed doing the mods to the mill and lathe but I need a break from it now.

Ron