Member postings for Pete Rimmer

Last time I bought a m12 x 1 nut for a ballscrew it was left hand thread. Glad you didn't find that out after making one.

VERY variable Anthony. Rarely a perfect square and often not even square-sided. Ok for rough stuff but I'd put a mic across each end of each pair to check they are actually parallel.

Can't argue with that philosophy Mike. You work with what you got and there's often an enormous gap between perfect and adequate. You wouldn't strip and scrape a machine for 2 or 3 tenths wear so if that's the best your tools can get it you're no worse off than if it was that much worn.

The sensible person would always check their straight edges before use especially if there's been a long interval since last use. I have an as-new 48" cast iron straight edge that I don't use but check the others against. The only thing that tells me that this 48" is not moving is that the other straight edges all check against it. If one day one of them didn't, I would check another. Two straight edges are not going to move the same so the second check would identify which part has moved.

Really though if they are correctly stored a commercial straight edge should stay straight fairly indefinitely. It's tools you make from cast iron that you should be careful with checking before use. As for granite moving over time, I never experienced that nor met nor talked with anyone who did. worn, yes but warped no.

Another supplier is United Cast Bar they also do GD250. Call them up and talk to one of the sales team, they might have a piece on the shelf. They also have a Kendall milling machine so they can pre-finish any part you order. I bought 3 metres of iron bar from them for the scraping class and they did give a good service.

United Cast Bar (UK) Ltd
Spital Lane
Chesterfield
S41 0EX.
Telephone: 01246 201194
Fax: 01246 540434

Sorry Marcel I mis-read your opening post, plus I wasn't familiar with the arrangement despite David George's description .

Anyway, looking at the photos the inverted vee controls skew on the y-axis slide so if you're getting some then it suggests that the slide is not sitting fully on the vee. I would strip off the table and the cross-slide, clean it up and inspect the y-axis slideways. Could be it's riding on debris or might simply be wear in the vee ways. If it's wear you're going to have to scrape it some.

I was going to suggest similar - a grub screw and lead pellet.

Last weekend I had a visit from a Norwegian friend who was over for the Ally Pally show and we were discussing this very thing (the difficulty in finding used straight edges). He told me that by far the easiest place he knew of to find cast iron straight edges was Sweden.

If you're in Sweden and struggling to find them I don't know what I would suggest.

Edited By Pete Rimmer on 23/01/2019 20:57:58

I did that, it bent like a banana though I did try to mill it from round, not square. I then got hold of some dovetail pieces which were slideways off an old machine and scraped one of those as a prism for doing cross-slide dovetails. That worked well but 6 months later it had developed a 2 tenths bend. Didn't take much scraping to fix it but I remind myself to check it on my plate each time I get it out to use it.

Edited By Pete Rimmer on 23/01/2019 19:17:28

A lathe bed can be twisted and still cut parallel. The headstock might not be square with the bed and someone shimmed the legs/bed to make it cut parallel in the chuck then set the tailstock over to cut parallel between centres (for their test piece) but a twisted bed means that the saddle isn't sitting fully on the ways which means more wear in the ways and in the saddle and a less rigid machine overall.

It's quite important, though some machines are immune to it. Hardinge state that there is no requirement for levelling the HLV for example. The bed is spring-mounted to the cabinet.

The frame levels have all sides finished square to each other so you can use it to check perpendicularity and parallelism if you like. They come into their own when working on a milling machine or other machine with vertical ways.

Parts are heated in a stress-relieveing oven to a specified temperature over a specified time period then controlled cooling. Any good heat treatment place will do it.

Raw straight edge castings need stress relieving. The HKA-x ones you see on ebay are King design and the finished ones they used to sell were stress relieved, rough-machined, stress relieved, machined then scraped, sometimes with a third round of stress relief thrown in. The ebay ones have one round of stress relief and are said to require no more but it's still possible they would move during machining.

Even old, previously-finished straight edges can develop a twist over time. I bought a 36" one which looked pretty good but had about half a thou of twist in it.

Don't know of any new finished ones in the UK. There's a guy in the South West sells the odd casting for 12" dovetail straight edges and they are nice to scrape in but you'll have to machine all the working faces first.

Kblast straight edge

Other than that you can buy King castings off eBay but they also need machining, perhaps stress-relieving and then scraping to finish before you can call them good to use. You're looking at 400 quid for an un-machined casting, plus import and vat most likely.

Used ones are very thin on the ground.

Hi Marcel,

If tightening the gib lifts it off the ways then you have a wear issue. Might be that it;s been run a while with the gib loose and worn a ridge that it's pulling up onto when the gib is snugged up.

Pop some photos up to show exactly where the problem is and you might get some good advice on how to improve it.

My Bantam had 26tpi on the gear chart.

I have several VFD's - Omron, Vacon, Yaskawa, Weg. By far the easiest and most intuitive to set up is the WEG aided by the excellent manual. I just got the Yaskawa today and though it has a myriad of setup options which would make it very versatile the manual is not so intuitive to follow. The Vacon one was also quite clunky to program. Both the Yaskawa and the WEG have dc injection braking which is very handy.

Andrew - my V1000 is also single phase but retains the three incoming power terminals, terminals 2 and 3 being bridged.

I think the chipmaster is the same as the Bantam, 9/16" diameter 10tpi pitch .200" lead left hand 2 start. I could possibly be able to knock out an EN8DM threaded blank to splice into your screw but I'm really busy right now. They are expensive because of the integral gear which I could also probably hob but if it is the sliding spline type, I have no cutter for the spline.

20 thou runout is like 20 miles for a gear cutter for clock gears.