Member postings for RJKflyer

Yes John, I agree, but wanted to be confident it was at least doable, as the TiN wheels I have in mind will cost 4 times the tool... (but worth it as always for the right tools).

Purists, please turn away now.

However, for the more adventurous/tolerant of you, it is possible to do some simple knurling using the vertical mill. I simply don't have space or resources to justify a lathe as well as a mill...

https://www.youtube.com/watch?v=rgon6wE9whs

Clickable link added.

Edited By RJKflyer on 20/07/2015 19:44:55

Edited By John Stevenson on 20/07/2015 19:58:47

Edited By JasonB on 20/07/2015 20:01:54

Yes I spotted the N/cm2 bit for one MC - it was 27, which is about 40lbf/sqin. This seems pretty low when you start to calculate the cutting forces and add on the safety factor and coeff of friction for an oily bed.

Yes, interesting re lathe use as this is possibly the worst type of 'disengaging' action - a complete twisting of the workpiece???

Also, looking at the page MichaelG links to, I see flat mag chucks annotated "Standard shape of magnetic chuck for most grinding, cutting, milling and lapping purposes."

I've seen a few threads asking about magnetic chucks, but they've not (so far as I could search) been very illuminating (to mix metaphors...!)

I have a Wabeco mill and am curious as to whether I could use a quality magnetic chuck on occasions when it would be very convenient (and possibly more accurate) to be able to access '5 sides' etc. without removing the workpiece.

There clearly ARE many quite industrial MCs on the market for pretty substantial work in a mill, but has anyone used an e.g. 6" x 4" Vertex or similar to do milling work?

(And, yes, I know that I could probably spend some time setting up the workpiece with all manner of other bits and pieces I have, but that's not my question!)

I appreciate that it would need extra care - flatness, cleanliness, adequate pole coverage etc.

Many thanks.

All I have is an 12mm thick aluminium backplate that bolts to my chuck with 4 cap screws, and the ali backplate has a raised centre spigot (only about 5mm) which fits snugly into the hole in my rotary table.

The backplate overhangs the chuck by about 10mm and has four holes in it to allow bolts to drop through to the T-slots in the RT.

Isn't this easiest, and possibly best? No risk of anything unscrewing, self-centring and no intrusion into chuck or table.

Thanks Colin - yes this is what I figured - potentially ideal for ali where one can tend to get a rougher thread from 'cutting' vs. forming.

I appreciate the frustration - I spotted that mine was very slightly off after facemilling (2.5" what was about a 3" square piece of 1/4" plate. It had the very smallest 'dish' in it which was only visible on blueing it onto a surface plate, which I realised meant the mill head wasn't 100.00% square to the table. It was a thou and this means about 0.046 degrees error in my case.

Needless to say, spent a lot of time fiddling with it - probably striving for unnecessary accuracy - and as the OP and others note, after all maner of careful setting (mine has a dowel pin for location) it still 'slipped' on being tightened up.

What i ended up doing was nipping it then carefully use a dead blow rubber mallet to get it spot on as i progressively tightedn it all up. Else no matter how careful I was, it 'slipped' ever so slightly if I just did it up in one go from the point it was supposed to be square.

Personally, 0.01mm over 230 sounds more than good enough - that's 0.0025 degrees.

One 'idea' I have seen is a small block bolted tightly to each of fixed and movable parts of head (as far from pivot as possible obviously) and an 'adjusting' screw to force them slightly apart to true up small errors that appear as you tighten. A bit Heath Robinson but esentially a mechanised method of what I do...

I have an opportunity to acquire some of the above quite economically.

At present I use hand taps, albeit in the mill with an excellent Walton pilot handle.

Given i do quite a lot in aluminium, wondered if it was worth trying some thread forming taps - any thoughts/guidance? Is this practical to still do by hand - I'm thinking M3-M6 only?

I remember this same challenge when I started out.

My initial answer was to do two things:

1. To work out the backlash in each scale so I could mill 'back and forth' in a slot (As you mention) without contantly making it slightly larger!

2. To add a couple of differently coloured small circular stickers to the fixed part of the wheel scale and ends of mill table so I could see at a glance which way turning the wheel would move the table (prevents the 'oh bugger' moment when you mill the 'wrong' way).

I have to say that now with digital scales, problem (1) is solved and problem (2) has mitigated with experience. However, I have to say (2) does very occasionally still happen - perhaps I should put the stickers back on!

Edited By RJKflyer on 12/11/2011 16:46:44

Edited By RJKflyer on 12/11/2011 16:47:11

Edited By RJKflyer on 05/01/2011 17:36:19