Member postings for Dave Halford

Speaking from a position of very little experience, I've never been able to get my head around using a rear-mounted toolpost and normal forward rotation (with inverted tool) as the cutting forces would try to lift the back of the saddle. Surely not what it was designed to resist?

However, so many people swear by it, it must work

Also confused by SOD's assertion that in normal use a front-mounted toolpost can lift the saddle??

Rob

I mounted Dti on some part of the lathe and run the saddle up and down.

I use mine all the time to know how much of a cut I have put on or to position the tool as the saddle handwheel is not accurate and you are guessing anything much less than 10thou.

Hi Dave,

Thank you very much.

>Looks like a T&LM style split cone head stock

Does there tend to be there more information available about T&LM lathes than about Mikron lathes?

>You edge them tighter as in 'loosen the back and tighten the front in small amounts with a C spanner till the play goes.

Thank you very much - that's an enormous help - I hadn't been able to find any documentation on it so it's enormously valuable to know that that's how to adjust the bearings. Is it reasonable for me to expect to be able to get rid of c. 1 mm radial play by adjustment alone? Should I attempt to clean out the bearings with solvent then compressed air to remove old oil and other debris then lubricate with fresh lubricating oil before adjusting?

I don't even know at the moment what lubricating oil specification would be suitable for bearings like this.

>It's very likely the bearings are fine, but they have been loosened to mess with the belt

Thank you very much. I don't fully understand "to mess with the belt" - unfortunately my generation were taught CNC and got no training in belt driven equipment. The motor and belt drive hardware that would have originally powered the lathe was all long gone when I bought it so I'm planning - without making any modifications that damage this historically significant lathe - to power it from a modern variable frequency motor and variable frequency drive that I have here or to buy a modern geared stepper motor to power it - hopefully if I get it right the geared stepper motor would have the advantage of allowing the lathe to be used as a divider and simple machining centre as well as a traditional lathe.

Thank you very much again for your help!

Will

So, I wanted to come back to the forum to add the solution I came to in the end.

First of all, thank you all for your thoughts and suggestions. It really did help me understand the problem and options for a solution, of whic there were clearly a few!

I ended up going with dc31k and ordering a boosting vfd. It arrived from china yesterday and I got it wired in today. It allows me to retain the 2 speed motor, so I can use the switch to go to high and low speed (though I accept that the VFd will also do that, and also the raglan has a nifty system of adjustable pulleys to alter speed, exactly like a CVT type transmission).

Anyway I bought this. https://a.aliexpress.com/_mtJ5IkI

Its labelled as an he200 vfd.

Cost was £61.71 delivered to my home. Instructions were in mandarin, but the seller emailed me a link to English instructions on request.

Easily wired up, and it performs perfectly fine. With the mill set to "high speed" on the switch selector, I do have to give the spindle a quick spin to get it going, otherwise it just buzzes. Once it gets started it accelerates well and has sufficient power for what I need.

Once again, thanks to all for your advice. I'd never have got to this point without your help.

Why should one invent a new rack size. There is no law to say it has to be an integer number of whatever you choose to measure it in. It’s still one rack width in parsecs.
regards Martin

Ive used a few and I can’t ever remember measuring one. The more useful measure is the horizontal pitch (hp) of which you can get 84 in the card cage

Edited By Martin Kyte on 06/03/2023 17:24:00

The thing you are measuring is not intrinsically metric or imperial, your choice of measurement systems is. Horsepower is not imperial neither is it metric but based on the output of a horse. Actually the rate at which said horse could raise a weight of 550 lbs or 250kg through a fixed distance of one foot in one second. It may perhaps be better described as an equine system of measurement if you really want to ascribe it to anything.

regards Martin 🥴

Hmmmm! Devil's advocate time 😁😁

I believe James Watt's original calculation was indeed 550 lb/sec or rounded up to 33.000 ftlb a minute. It became known as the mechanical or imperial.horsepower....but there's this thing known as a metric horsepower or PS which is slightly smaller at circa 542 lb/sec or circa 735 watts.😄😄

Cheers.

Stewart.

Edited By Bdog507 on 06/03/2023 14:54:23

I was not aware of that, I wonder why someone decided.to create a new standard when it means a lot of equipment won't fit. I am sure you can get narrow 19" racks, that just leaves less room for cables down the side of equipment.

I've no recollection of what we measured things in @ school, should have been metric i guess, but i've always done a rough in head conversion depending on what i was measuring. (now a more exact conversion with attempting to be a hobby machinist)

Flit from one to the other.

Big things~ feet.

Under one foot, i find cm convienient.

Little things~ well a thou or ten seems a lot more convienient than .0..whatever mm.

The Imperial system was,at least in part developed from the natural order of things?an inch~ width of your thumb, a foot~ well self explainatory as long as you have large feet , etc etc.

The Metre as i understand it, is the length it is because someone just decided it was so & bears no real relevance to anything real world. They just said a metre is 'this much' & we'll use that.

Metric system short changes you 4" x2" x 8ft Timber? you'll be lacking on all dimensions with metric.

Ever run the mile? Nowadays it's usually the 1500m.

All that said Duncan's probably right, the Imperial system will likely peter out eventually, when all the old & wise have departed this life.

Sometimes the' best' isn't the popular choice. Anyone remember VHS & Betamax?

Betamax was actually technically a better system, whilst being smaller, but Jo public went with VHS.

Whilst dave is right it is often easier to fix a broken wire rather than a computerised system. Noel.