Category: Equipment

Finally! The mill arrived!

After 6 months of waiting I noticed Chester had the Eagle 25 mill on special offer. I called them and found out that this indeed meant the new lot of mills had arrived!
I borrowed some money to pay off the outstanding bill on it and got delivery arranged as soon as possible, since I didn’t want mine to be the last of the lot for a couple of reasons;

  • If there was something wrong with it, I wanted there still to be one to replace it with.
  • If I waited until there weren’t many left, I’d risk getting the obviously less than immaculate ones.

So yesterday around 3pm, it arrived!

I’d had some trouble with Chester when trying to find out how large the actual crate would be, since it was coming to a domestic property and we have a nice domestic garden-gate it’d have to get through. I’d been told it was 90cm wide, so to expect packaging a few cm larger than that. So as a result I was fully expecting to have to dismantle it on the pavement outside to move it in.

Fortunately the crate, once off the pallet was just small enough to fit into the front garden. :)

The reason for this was it’s packed diagonally to save space, so the crate wasn’t as wide or deep.

And there she is. :3

Checked the manual and with help from Andy, broke it down into; the base, motor, headstock, and column. Then we lugged it through to the workshop.

Whew! That’s a hell of a weight off my mind now.

I generally like the layout, though there’s a couple of niggles; the belt housing lacks an extra hatch that’s in the manual so it can be opened when the head is in a lowered position. It also has mains cabling running through it within milimeters of the spindle pulley. The quality of the table casting is also a bit rough. But of all the Chinese tools I’ve bought it’s probably the best, and I bought it understanding it would need tweaking.

It’s the R8 taper version with metric leadscrews (2mm pitch). I’ll need to make some adaptors and stand-offs for the the table portion.

The top-box should come off fairly easily, though the spindle pully is a lot larger than I expected. This might make it trickier to position the big DC motor. But overall nothing has been thrown up that can’t be overcome.

I’m going to knock a couple of other small projects out of the way before I really get started on it, but should be able to work on it pretty easily come the new year. :)

Late night confession

I’m a bit afraid right now.

The milling machine’s been delayed another month. ETA is now early December. But I’m not complaining. Technically I don’t have enough money for it anymore. Once it arrives I’ll have at most a fortnight to pay the rest of the outstanding balance.

Since the £700 set aside for it was going to be sitting in my bank account for some 3 (now 6) months longer than expected, I decided to try and grow the money a bit before it went finally into low-fluidity material goods.

I’ve been spending a lot of money this week. A lot of it either on repairing or replacing tools, but mostly on these horns I’ve won on ebay tonight and the upright rotary table for the 4-axis mill project.
And I’ll be spending more once the horns arrive. I’ll be casting a lot, painting, trying out foam-rubber casts, mostly in the hope of getting enough wonderful quality items ready that I’ll be able to storm both Etsy and MCM Expo with them.

I think I can do it. But I’m still gambling again. And to be honest with myself, my previous gambles haven’t had very good returns.

It’s a supportive routine though. Waiting for supplies and parts to arrive sets me up with a waiting list in my mind, so I get on with immediate jobs a lot faster.

All I do is talk about what I do now. I’m sorry it’s likely not a very interesting subject to most.

Backlog/owed items are almost all done. Legacy projects are either scrapped or progressing. Things are generally improving. Life’s clearing out the chaff.

Will try and get back on Skype in the workshop again tomorrow. Talking while I work may help further.

Enclosure arrived!

The enclosure found on ebay arrived today. My guestimates (since internal size wasn’t mentioned) look to have panned out, and it’ll contain all the parts quite nicely.

Fortunately I had a piece of aluminium plate left over from my grandfathers materials which will provide the needed backplate for the plastic box. It feels nice using something that was his in any of my projects.

The driver board will just about fit in, though I’ll need to be creative with mounting the power supply. I’ll be cutting some holes in the top access panel for the driver’s D-connectors, the IEC connector will probably go on the top or side where gravity shouldn’t let it fall out. Bottom is probably going to have the illuminated mains switch and the five 4-pin XLR connectors for the steppers and motor drive. The left-hand panel will have the filter-protected exhaust vent.

A fine wire filter grill will be going on the front panel to direct air onto the PSU, which will flow across the box and out the exhaust. The box should be kept at positive pressure. The box is far more environmentally sealed than I really need. All I really want to ensure is no dirt and spiders get in it.

Also found a few little 12v fans that should replace the defective one on the driver board. Got a 24v 80mm fan for the front that came off an old LaserJet printer. Not sure where to put the emergency stop yet. Got to be the soft-off interlock on the driver board I think, since cutting power might still leave steppers moving for a short time. Also might not want it on the enclosure itself, but remote.

Mounting the readout is also a puzzler, but can be done later.

Bothersome circuit

Very tired and about to go to bed, but traced and ID’d most of the parts on the old treadmill motor controller board.

It drives a motor rated for 180v DC, but my measurements say it’s putting out 330v DC which would make sense for rectified UK mains. I suspect on looking at the board that for UK use they dial the speed control trim-pot down to half so the PWM signal never goes above 50%.

Still means the motor’s running at twice the voltage it should though, which’d explain the overheating issues.

I don’t understand the circuit fully though. For one thing there’s a half-bridge rectifier essentially bridging the motor terminals. Surely that’d mean it’s perpetually shorted out? I don’t understand it, but suspect it might be something for dealing with back-EMF from the motor.

I also don’t understand how the MOSFET’s driving it. It all seems to be coming through a 5Watt resistor and some very thin traces, especially since the motor’s 2-2.5HP (1400Watt+). Maybe it’s because it’s late, maybe I’m just not seeing it and it’s just the trigger. Just can’t see it right now. But the circuit does work (even if the fuses and current breaker don’t. If something shorts it ALLWAYS knocks out the 30Amp breaker for the workshop).

It’s a single-sided PCB. Here’s my notes on it. A few figures are missing, but all components are marked.

I’m planning on making a much simpler control circuit, but it does involve a very large 220-110v transformer to get the proper 180v DC.

It’s been a good day. Castings done, experiments done, oscilloscope usable again, found artial pressure cooker for new vacuum degass chamber, some clearing up done.