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. :)

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.

New Mill Project

With the money I’ve been gifted, I’ve just put a deposit down on a BIG milling machine in the last few hours it was on special offer pricing. A Chester Eagle 25. I’ve also bought a Chinese 4-axis CNC driver board.

The mill is out of stock currently, so I’ve got a 12 week wait there probably, and 12-24 working days to wait for the driver board. Once the driver board’s here I’ll be grabbing the four steppers and PSU rather than have them sit around untested. :)

While it sounds like an unpleasantly slow process, it will give me the extra time I need to sell the current mill and replace workbenches it’ll all be going on.

The new milling machine

I bought a milling machine! Let’s see what I got and what I need to do to it.

One of my brain-relaxing passtimes is to randomly browse ebay for interesting machines, broken items for spares/repair and so on. Like Thomas Edison said; “To invent, you need a good imagination and a pile of junk.”
Of course Edison didn’t have access to ebay or Google Image Search, so while I have a nice pile of junk, I can add a whole lot of extra random inspiration to it by just browsing images of junk.

One of my searches is usually for mill or lathe parts, to see if there’s any out there I could put to good use. I’ve been hoarding parts with the hope of building a mill or better milling accessory for my Conquest Lathe. Even a second-hand tiny mill will still run to well over £200, so my best chances of getting something within my tiny budget are:

  1. Find a machine so broken it’s cheap, but damaged in such a way I alone can fix it at very little cost.
  2. Find parts of other machines that I can assemble into a working milling machine.
  3. Find a machine strange enough that few other people will bid on it.

Last week, Option 3 occurred on one of my browsing sessions. And I won it.

Small Homebuilt Milling Machine In need of attention to bring it up to a good standard the drive pulleys do not match exactly , although 2 or 3 speeds are available

there is play in the rise and fall of the headstock and a clearance problem with raising the head fully , maybe a bit of re-design needed!

the table has been fitted with a thrust Bearing and 1 end modified to accept a power feed unit but was never fitted

the table and / or the headstock needs a bit of shimming to get true machining

heavy fabricated steel construction with 370 Watt 1/2 Horse Power Single Phase 230 Volt Motor with Full Overload Protection and remote Stop/Start Pushbuttons

A good quality Cast Table , Size 475 x 154mm (Table cost was £100 ) 1/2″ MT2 Chuck with M10 Thread Drawbar Tilting Headsock ( left / right )

Adjustable Taper Bearing Headstock overall height of machine is 960mm depth is 600mm table to chuck height Max. 250mm Weight aprx 120 Kilos

Some light water marks to table due to garage roof leaking but not serious

please ask any questions i can e-mail more photos if required

£50 delivery on a pallet OR collection from Braughing , near Ware , Hertfordshire OR arrange your own collection

Mainland UK delivery only NOT to the Highlands or certain places in Wales,please ask

Payment by Paypal Only within 3 days of auction end

Happy Bidding!

A home made machine! Perfect!
Collection verses a £50 shipping fee would further lower competition, and it was just 30 miles north of me. And while I don’t want to offend the builder of it, the punctuation in the description probably doesn’t inspire the confidence for others to give that extra bid.

All in all, a prime listing for getting a bargain. And at £155 for 13,700cm3 of machining capacity, that’s a bargain in my books.

Now while I’m going to have to discuss the machines faults, I again don’t mean to offend the builder of it. It’s in my estimation the same sort of machine I’d have built in 18 months or so, with a few hundred quid in parts and the same development feel (initial planning, careful use, leading into jury-rigging just to get it finally working). So this machine has saved me a year and a half and a hundred quid or so. So I can skip straight into taking this messy but functional machine and refining it.

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