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Messages - BluePinnacle

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151
This is the way some of the big Leifeld lathes do it, other "playback" lathes use encoders on the cross slide and record a route as the roller is moved across the face of the tool. The "gap" can then be set for a basic material thickness and edited to allow for thinning or compression.

I think Mach3 has a tracking facility but I've never used it. Suggestions from the audience?

152
General Mach Discussion / Re: RoHS and CE Compliance
« on: February 08, 2010, 07:33:55 PM »
The CE mark is a fairly general quality/safety mark for almost anything sold within the European economic area, and RoHS is now firmly in force for all but the military. So basically anything you buy new in Europe will almost certainly be compliant by now. Is this an end user requirement? It's not a hard one to meet.

153
Wonderful project! I used to have a model 29 classic hunter, 8" full lug barrel and unfluted cylinder, delicious fun and a great way to turn railway sleepers into firewood.

Ideas for the barrel: Use a section of .177 airgun barrel? Or use a bit of it for a guide to gradually scrape out grooves? A spring loaded cutter at the tip of the rifling tool would be easy enough to make, and would just wear a groove gradually. File the rifling out very carefully at the crown of the barrel to make it look deeper, if you need it, and if you can find a file that small :)

154
Show"N"Tell ( Your Machines) / Re: CNC Welding...
« on: February 04, 2010, 03:58:42 AM »
the big rectangular flanges I put in my show-and-tell page were for another accelerator ;) not superconducing though.

155
^^ Yeah, that's the other way to do it :D

I've come to the conclusion with my two spinners - Who have clocked up around 40 years experience between them - that it's not quite as simple as it looks, never quite obvious in its mechanism, and flexible enough that it is either surprisingly adaptable when required or utterly treacherous. I think they may be Jedi on the quiet.

incidentally I've just worked out that the contact speed of the edge of a big dish blank, when it is trimmed off with a lathe tool, is over 4,200 surface feet per minute, so it's hardly surprising the swarf flies about like it does.

156
My best guess would be to spring load the tool or use a load cell or other indicator.

Large CNC spinning lathes use hydraulic rams with (I think) linear encoders. very expensive, especially if someone plays with it and drives the ram into a rotating tool that weighs as much as a fully loaded pickup truck. It has happened.

157
Show"N"Tell ( Your Machines) / Re: wiring guide fun
« on: February 03, 2010, 02:29:59 PM »
I have plenty of lead solder :)

OpenOffice is very good for doing layouts, all the way up to fairly decent technical drawings.

158
Good work, lighting - lots of work for the right spinner. We do all microwave stuff, generally C-band to Ku band with the odd one at nearly 40GHz. All ours are hand spun though.

If it helps, large PNC machines usually have a roller of a known shape which is moved across the static tool, and the path recorded, then the gap set according to the stock material thickness and the path recreated based on this - Thus arbitary shapes can be reproduced easily. There's more to it than that of course, it's very much a learned skill rather than a fixed process.

Errors on parabolic reflectors are usually measured using photogrammetric modelling: lots of dots and a couple of coded targets are photographed from various angles using a very decent digital camera; all the shots are then fed into a laptop and the target dots' position calculated relative to each other and relative to a 3D model of the dish. the software is called Photomodeler ... it's very very clever.

We can hold 0.6mm RMS surface error on a 3 metre dish ;)

159
General Mach Discussion / Re: Stepper Motor Question
« on: January 30, 2010, 10:29:04 AM »
The other problem I've encountered is that the processor load exceeds the processor's ability to deliver signals. When this happens all hell can break loose. Go to the diagnostics page, watch the processor load bar go up and down as the program executes. If it breaches 100% at any time you're on course for a program crash. The only cure for this is to reduce the pulse rate to the steppers.

160
General Mach Discussion / Re: Fine Saw dust
« on: January 30, 2010, 09:32:11 AM »
magnets are good, in  case of collision it has a good chance of just falling off instead of getting smashed.

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