Author Topic: Single point threading accuracy (Read 12268 times)

Twinsquirrel · « **on:** February 12, 2009, 04:27:56 AM »

Hi all,

I have an old imperial cross slide of unknown origin which I want to use as the basis for a vertical slide for my mini-lathe, of course it would be nice to convert it to metric while I am at it.

Do you think the mini lathe is accurate enough to cut a thread for the x-slide screw, how accurate does the thread need to be and how do I measure it?

Thanks in advance

David

Darren · « **Reply #1 on:** February 12, 2009, 05:28:14 AM »

I did a post on this here http://madmodder.net/index.php?topic=460.0

I think a rolled thread would be better than a cut one as it will be a lot smoother to operate. Therefore give you a better finish on your work.

BTW, the mini is fine for cutting threads, plenty of peeps make some really accurate threads for scope lenses and such.
I've only tried a couple of times myself and it seems ok to me.

NickG · « **Reply #2 on:** February 12, 2009, 07:18:26 AM »

The only limiting factors will really be the pitch error of the lathe and your ability to machine the thread! If it's not accurate over the full length of thread, your handwheel graduations won't give you the right distance! The easiest way would be to leave it and find a digital scale? Not sure how good these are? They seem OK for vernier calipers. I am planning to put these onto my vertical milling machine as although it's supposed to be imperial, it's not very user friendly graduations! I know it's a cheap and cheerful DRO and the glass scales must be far superior but they are far more expensive too!

Nick

Twinsquirrel · « **Reply #3 on:** February 12, 2009, 09:29:14 AM »

Aaah Thanks Darren, It seems there is nothing new under the sun!!

Nick, I'm liking the idea of scales very much, I think I will do that first as in my mind I had this as a scrap box project and do the screw replacement at a later date.

Cheers both

David

bogstandard · « **Reply #4 on:** February 12, 2009, 10:45:32 AM »

David,

Digital calipers costing less than a tenner can easily be modified to fit for uses such as yours, my old mill used to have the digital type scales on all three axis and they worked just fine, as long as you can keep swarf and moisture out of them.
A quick strip down, clean and dry out got them up and running again. Oh, and a dozen batteries in stock, once they get wet, the scales tend to eat them like they are going out of fashion.
I still use one on my new mill, for the quill feed, and it works perfectly. But I have fitted a remote readout, and a mains transformer kindly supplied by another member on here. Only because of me, making life easier for myself.
They are usually accurate to 0.0005" (0.001mm)

I have gone over the top with my machines, but you would find, even cheapo scales can allow more accurate and easier use of your machinery, and can transform difficult jobs using handwheels, into run of the mill machining exercises.

John

sbwhart · « **Reply #5 on:** February 12, 2009, 04:47:35 PM »

Hi David

I fitted a DRO to me 3 in 1 and found it quite simple to do and a very useful addition.

http://madmodder.net/index.php?topic=540.0

Cheers

Strew

NickG · « **Reply #6 on:** February 12, 2009, 04:52:25 PM »

The quill feed on mine has one too and it seems to work well, as you say Bogs, I think the batteries could get quite annoying though!

I was looking at these: http://www.machine-dro.co.uk/index.php?target=products&product_id=111 Still quite expensive though, would be the best part of £500 for a 3 axis by the time you got the scales and covers ,which is nearly as much as my milling machine cost! However, from my experience of using them at University, if they were installed correctly it would transform the machine! They have other features on them too, such as PCD calculation etc.

Nick

John Stevenson · « **Reply #7 on:** February 12, 2009, 05:02:41 PM »

Try these fixed price DRO's.

http://www.onyx-dro.co.uk/

I have bought the 3 axis mill DRO and the 2 axis lathe DRO in the last year and I'm very pleased with them.

Support is brilliant

JS.

NickG · « **Reply #8 on:** February 12, 2009, 05:59:49 PM »

thanks John, they look like a really good deal!

bogstandard · « **Reply #9 on:** February 12, 2009, 06:28:58 PM »

Hey John,

Where were you when I was buying my setup? You could have saved me a decent wedge.

I searched everywhere for mine, and that link never came up.

The only decent one (other than ones who thought theirs must be solid gold, for the prices they charged) was the one that Nick came up with, which was the eventual winner.

John

Bernd · « **Reply #10 on:** February 12, 2009, 06:40:17 PM »

Ow, John, that light looks familar.

Is it a Waldmann?

Bernd

bogstandard · « **Reply #11 on:** February 13, 2009, 01:48:18 AM »

Hi Benrd,

No idea, it is just a very bright halogen light to me, and it gets rather hot, but it is a steamer.

When spots of coolant hit the glass, I get little puffs of steam.

John

Bernd · « **Reply #12 on:** February 13, 2009, 04:24:41 AM »

Looks like it could have been, since you don't have the machine anymore.

Ya they do get hot. 24V halogen bulbs in these also. Don't have the arms that go with them. Like to mount them on the Bridgy. Price was right too, $0.00 for two.

Bernd

CrewCab · « **Reply #13 on:** February 17, 2009, 03:55:50 PM »

Quote from: Bernd on February 13, 2009, 04:24:41 AM

Price was right too, $0.00 for two.

You should have bought 4 Bernd

CC

Bernd · « **Reply #14 on:** February 17, 2009, 04:41:40 PM »

Quote from: CrewCab on February 17, 2009, 03:55:50 PM

Quote from: Bernd on February 13, 2009, 04:24:41 AM
Price was right too, $0.00 for two.

You should have bought 4 Bernd

CC

Wife could only find two headed for the scarp bin. (know what I mean?)

Bernd

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