Amadeal AMA25LV conversion

[Doug]

So I start off with my incredibly cheap mill bits from auction £20 for a mill base on a stand with a working glass scale DRO system attached with column but minus the Z axis casting. I also have the mill head but minus the electronics for the DC spindle motor. The two missing bits while problematic for most (which is why I suspect the mill didn’t sell easily) for me it turned out perfectly. I already had my Seig X1L mill that had an AC spindle motor with VFDrive and a Z axis already to go.

[Doug]

The head is a solid casting with two speed gearbox and a quill feed oh and an R8 taper.
I have lots of drawbars and R8 tooling so all looking very good 👍🏻

Both my Z axis and the back of the head have flat surfaces that can bolt together. I turned up a round spigot so the head can pivot a bit on it to tram the head in. I don’t want full rotation as I have other ways of doing that.

The head also has a readout and I slapped an 2032 battery in that and away it went, this purchase must be the Engineering bargain of the year. 👍🏻.

[Doug]

So a good few years ago I built a “strong back” frame for my old seig mill to try to add some strength to the column this is the perfect size for the frame of the new mill. My plan was to bolt the X/Y to the base and the Z to the back and eliminate the old column. So I had to strip the whole lot down and remove the lead screws and DRO
A very sad looking pile of mill bits. The Z axis I made a while back needed some work first to be able to mount the head so I attached a hand wheel to it to move it about to calculate the center of travel for the spindle.

Here you can see the spigot and the three mounting bolts that hold the head. It’s all very heavy and I can only move it about in bits.

Here is the strong back arrangement.

[millman]

That will do the job nicely Doug. Not surprised you have to move it in pieces, it looks heavy.

[Doug]

Oh yeah I tried to lift the Z axis with the head bolted on and it was a no go, the XY tables too, had to use an engine hoist to lift that.

[Doug]

So the next job was to get the ballscrews to fit, this involved some angle grinding to cut them exactly to length and some turning. To do that I had to take the ballnuts off. This isn’t as hard as it seems as I turned down some nylon bar to the same dia as the ballscrew lowest dia and just wound the nut off the screw onto the nylon “keeper” I then turned down the ends to suit the floating bearings. The ball must being bigger than the lead screw nuts ment I had to mill the XY casting, the nuts are held via two screws through the casting so I just had to make the two holes bigger on my old mill in one go so the angle was exactly 90 deg.

Then with the ball screws fitted I could trial the head and swap the DC motor for my AC motor


It fits just!! A quick run up confirms the gears are working and I can use both speeds on the gearbox.

[Doug]

Next up was mounting all the parts together on the stand


Then adding the electrical box
And the screen

[Doug]

The next task was to make a chip tray and add guarding

Then needed to fit some hardware for counterbalance as this will be very hard to do later

The next thing after that is fitting reference switches to all the axis


This allows the machine to reference itself and I can then use software limit switch’s so I don’t run into the physical endpoints.

[Doug]

So this is how it looks now

Got to do the geometry checks and spray the guards, been distracted by fixing a panel on my motorcycle

Got a few bits to tidy up but it’s almost useable at this point, just as long as I don’t expect accuracy

[Doug]

I have now painted the mill and done all the geometry 📐 work. The y and z axis were very good the x axis I am not too sure about so may do some more checks on that. You have to tell the CNC program how many pulses to send out to the steppers to move a distance. The x and y should be exactly the same as they both have the same ballscrew pitch and are both directly connected to the steppers. The z axis has a reduction pulley and belt so that s slightly different. I checked them with the DRO and scales I took off so I would expect once set up the DRO and computer screen should show exactly the same distance z and y are both good y axis actually matches the DRO to 3 decimals it has a bit of backlash but they are cheap ballscrews the x axis I can’t get quite right but will do a better setup of the scale and try again.
Trimming the head in was just a case of fitting a finger clock to the head and doing a 360deg sweep that came in at a max of +20um and a min of -10um so I am not too unhappy with that if I want to get closer than that I need to improve the setup I have (fit 40tpi jacking screws).
Anyway almost ready to cut metal in the photo I have my machine vise ready to get some dowel pegs to the base so when I drop it on it can drop into one of the tee slots tightly so I don’t need to clock it up.

Oh I also had to turn up a drawbar for the R8 tools it was 7/16 UNF as is all my tools I guess that’s a Bridgeport thing. Anyway just got to wait for the paint to go off (bout a week I recon) and I can give it something to chew on see how it performs. Will also get the laser tachometer on it and see what the two speeds come out at.

[Doug]

Bit of an update I tried and tried to get on with the. Axis backlash which was quite excessive, I thought about swapping the whole thing out then remembered that the backlash is not in the screw but in the nut so I found another blunt and swapped that out. Went from 535um (yes over half a mm) to 35um still a lot by industry standards but for what I use perfectly fine and delt with satisfactorily with the backlash compensation it’s only showing a few um on test components. Anyway been making very small components for my loco on it and they came out very good so happy with the mill so far and I am using it a lot lately

Other issues found the quill lock wasn’t working very well and it was slipping found this to be the cone that should lock the quill had been greased which messed it all up.
I now have to reference the machine after first turn on and this then sets the soft limits which is great. Getting to play with the G54 etc offsets is good so can use multiple zero points and be able to switch between them is opening quite some interesting programming options. I may change up the tool change ring to lock the spindle for undoing the ER collets it currently uses a 6mm hole which I put a bar into and use a spanner on the collet, think I will change this for a slot for a c spanner.