Member postings for John Haine

But R8 collets much better....

Surely the "super hot steam" won't be hotter than petrol vapour burning with air? Why not use aluminium alloy for the block with inserted liners made of steel or meehanite? It sounds from everyone's experience above that titanium will be an absolute b***h to machine with no end of opportunities for things to go wrong.

I believe that the Tornado project to build a new full-size A1 locomotive converted all the drawings to CAD by scanning. Actually no, I've just checked in my workshop manual (a good read) and they were scanned to electronic form and then cleaned up, re-dimensioned and toleranced etc, but I guess when they needed to generate CAM files they must have been re-drawn in a CAD system. This would suggest you take the re-draw route.

Edited By John Haine on 21/06/2012 16:32:35

Indeed John, but it's a shame that the SX2 keeps the same downfeed arrangement as the X2, rather than a leadscrew. I know it's faster but as far as I can see the only way to get accurate downfeed is to measure it by adding a DRO or using a DTI. Rack and pinion doesn't seem to me to be the best approach.

In reply to John S, I'm not advocating that these machines should be high precision, just that they should have a spec against which you can buy them so as to have some recourse. I see so many tales of woe both here and on other sites about cheap machines and people seem to be so tolerant!

I have a Myford from Taiwan, a VMB, and actually I think it is a very reasonable machine. I have told elsewhere on this forum my only beef about it, which I easily fixed. It's a bit agricultural, but accurate and pretty sturdy and it cost about £1500 new.

I also bought an X1 from ARC to convert to CNC but decided that I wanted to get machining so sold it on to a mate and got a little Denford which is fantastic. ARC are a great supplier, but didn't take their prep service since I'd be dismantling the mill anyway. I thought the finish between the column base and the bed was lamentable, looked like the casting had been smoothed with an angle grinder so I machined the bed flat (it just fitted the VMB). Since then I've machined up a CI adapter block on the Denford for my mate and he has fitted the fixed (non-tilting) column from Clarke's and I gather it has made a huge difference to the accuracy and rigidity of the machine. I also thought the gibs were a joke, too thin for the gaps, bent, and roughly finished, so I made new brass ones at least for the Y and Z slides before I sold it which fitted properly.

I think that the ARC X1 with the long table with the fixed column from the Clarke version would be a better machine.

I think it must be worth asking the suppliers for a machine spec in respect of aspects such as table flatness, spindle runout, XYZ orthogonality etc. before you buy. These things aren't too hard to check and if they are not to spec SEND IT BACK! Just because a machine is cheap doesn't mean we have to accept rubbish - clearly some of these machines are quite good and some apparently identical are not. We ought to start behaving like consumers.

Well, I went the Corian route and the result is OK but not as good as I would have liked. Blowlamp, what speed do you run the cutter at for engraving Corian please? I used a 30 degree taper engraver cutter running at 5000 rpm, fastest my mill would go, but the letters are not cut all that cleanly. Anyway a good learning experience...

BTW if anyone is interested, I used a free open-source program called F-Engrave to generate the G-code. It's very easy to use though a limited set of fonts and you have to use the same font size and style throughout.

The chap I referred to above gave a lecture at MEX last year on behalf of SMEE - see

**LINK**

and scroll down to find the summary. You don't run them (alternators) as stepper motors but as polyphase motors where the stator phases are switched from rotation of the motor. Speed increases until the back emf equals the volts applied to the rotor, just like for example the outrunner motors used in R/C modelling. That's for a given rotor current - if you increase the rotor current then the motor runs slower but generates more torque.

A gentleman has exhibited at various exhibitions the use of car alternators operating as motors, essentially as "brushless" dc motors except with a wound dc-excited rotor instead of permanent magnet. Because the alternator uses slip rings instead of a segmented commutator, and the brushes carry only the excitation current, brush life is a lot longer. Except for the excitation current, speed control is by applying 3-phase to the stator windings and this could be derived from one of the standard BLDC controllers. There's also quite a lot about this on the web - google "alternator as motor". As alternators are made in large numbers for cars this seems a nice approach

Folks, thanks for all the ideas and suggestions. A local joinery has kindly supplied a metre square bit of white Corian gratis, so I'm going to have a go with that and filling in the letters with paint.

Thanks for the lacquer suggestion Ian! Round here we don't seem to get much criminal activity and they would get better pickings off the church roof...probablt famous last words!

I wondered about Corian, will look into that, thanks Martin.

I have (perhaps unwisely) agreed to make an engraved plaque for a tree planted to celebrate the Jubilee. Obviously this will spend its time outdoors, any suggestions for material please? My initial thought is to use ali as I have some 10 mm plate to hand, with a mounting post of stainless steel tube, with stainless fixings. Site is well inland and rural so salt and pollution level is low. Will engrave on my CNC mill and if possible do an intaglio job with a black wax or resin in-fill. If possible will also use some kind of passivating coat or laquer on exposed metal surface. If it all works at a later date I might do a brass version but that sounds pricey! Questions:

• Any reason why ali should not be used? Will it just corrode too quickly (especially with stainless fixings)?
• Could anyone recommend a protective coating?
• Is there a source for some kind of engraving wax or resin (I know I can get black epoxy from Maplins, and one can even use Araldite mixed with lamp-black!)?

Any suggestions or ideas gratefully received!

Thanks, John.

Well, being open-source anyone can put forward a model, we don't have to choose! Lots of good suggestions above to get things started.

The other important thing is the copyright licence under which the design is published. This sounds boring but is vital. There are several models from open-source software, I'll do some digging around and suggest something if you like?

John.

Here is an idea - Open Source Drawings. Some of the best software around now is Open Source which anyone can download, use, modify, and (subject sometimes to conditions) re-distribute.

There are some very good freedrawing packages around - e.g. SolidEdge. Anyone can download these and use them for non-commercial purposes, and anyway quite a few MEs now have CAD.

So, if drawings were made available on-line in suitable format, then people finding errors could modify the drawings, improve them in other ways, submit them back with the changes to be incorporated in the orginal, and/or re-distribute them. There could be micro-businesses for those with CNC machines to make tricky or tedious components to order using CAM to generate Gcode from the drawing files (think, castings).

All this is possible now, ME/MEW could facilitate this. Of course it might threaten part of their business, but as the saying goes, if you don't come to the banquet as a guest you are likely to be there as the meat. How about it, Dave?