[Torsten]

It was -1C in the shed tonight and so a good time to set too and cut off the blank for the X axis nut mount. 40mins later 40mm x 80mm of steel gave way to the trusty hack saw. I squared the sawn face up on the mill ready for marking out the holes for the nut.

Wohw, you did this with your Hacksaw?
Impressive, you do have a lot of patience.
Good Job

[arizonavideo]

I don't understand why you used the hack saw. No chop saw or you just wanted to stop from freezing to death before you got the stock cut!

A bit different jig plate you using, do you jig everything?

[abfa9358]

No chop saw, all done by hand. The hacksaw has been passed down through three generations and still seems to cut pretty straight, not the same blade!

Bit more progress on the X nut mount. I've done all the milling and need to pitch out the holes and then bore and face the block. I think I'll do this on the lathe the ensure the mounting face for the ball nut is square to the base.

[abfa9358]

New Years Eve here in the UK, heres a summary of the last few days....

Prior to starting boring the nut mount to take the ball nut I took the time to check the lathe setup. I first levelled the head stock end of the bed with my precision level (0.0002"/10") and then zeroed out the bed twist at the tail stock end, final checks being made by cutting test diameters spaced by around 5". Initially the machine was cutting 3 thou up on the outer diameter, after a bit of fiddling the diameters were equal within the limits of my measuring equipment.
After that I checked the runout of my face plate, now 24 years old. Again a bit of runout and not acceptable as I planned to use the face plate to support the nut carrier whilst boring the hole for the ball nut. So I decided to re-face the face plate, this reduced the runout to basically zero across the enitre surface.

All good, so on to boring the hole for the ball nut, this went smoothly once I'd sorted out the feed/speed for the boring tool (see pic). Clearance on the nut OD is around 1.5 thou. After boring, I faced the surface on to which the flange of the nut would contact. So in theory the nut carrier based, bore and mount face are as orthogonal I can manage.

Tonight I tapped the M6 holes to take the cap screws and then decided to see whether it all fitted together - this could have upset 2010 New Years Eve. However, the whole assembly fitted perfectly, everything lined up, no binding - happy days!! This brought back nightmare memories of fitting the X screw to the X2 - angle grinders, dremels, shims, engineering nastiness Aaah!

Please see attached pictures.

Happy New Year to all on the 'Zone!!

[LongRat]

That's some nice boring work. You are going to have a really beefy set up there.
What's that lathe you have? Got a Warco 9x20 now but in a couple of weeks I am going to be picking up a very nice Boxford long-bed AUD!

[abfa9358]

The lathe is a Boxford ME10 purchased by my Father in 1986 and used to build a series of 71/4 gauge steam engines. I think you will be very happy with the AUD, note that Boxford spares are "reassuringly" expensive.

[digits]

Beautiful work!

I couldn't find it in the thread - is that a 16 or 20mm screw you have on the X-axis?

[abfa9358]

Thanks Digits, screw is 20mm dia from Zapp Automation. I had the nut reloaded with oversized balls to minimise backlash.

[digits]

I am always amazed just how different the saddle castings for a real BF30 and the clones are - that pocket you have mounted your X-nut in is on the underside of my Warco!

[abfa9358]

Longrat did you get your Boxford lathe?

[abfa9358]

Sorry should have combined these posts...

A bit more progress, after being side tracked making a number/door bell plate for the house and fixing my friends 30 year old “OO” gauge clockwork engine. I've finished the Y axis nut mount block, I haven't fitted it yet as this involves stripping the mill down (yet again) - I'll start that tomorrow night, all being well it should fit as well as the X axis and then I'm very close to fitting the motors and having a trial run of the X and Y axis. I’ll probably do this with a signal generator since the electronic sides of things is in a bit of a disarray as the old motherboard is new in my wife’s “new” PC. I haven’t had time to put the ITX mobo and MESA 7i43 card into a suitable box, I also need to build a breakout board… the list goes on. STOP think of the Shawshank Redemption, small chips and lots of time = significant progress.

One thing I did learn when fitting the X axis is that a silicon carbide coated tile saws from B&Q i.e. a wire blade that fits in the hacksaw, are ideal for cutting hardened ball screws. It actually cuts a lot faster than you think and gives a finish similar to an abrasive disk cutter, just make sure the screw and nut are completely protected and that everything is cleaned down before the protection is removed.

[LongRat]

Nice steel work there, I look forward to seeing your first motion - I still remember the moment mine moved for the first time... Sweet indeed :P

Oh and yes, got the AUD lathe in today. It is the 28" BC MK3 version, looks very nice. Looking forward to turning with it.

[abfa9358]

So finally, the Y axis is done....The nut mount fitted fine with just enough clearance for the cross stiffeners and everything runs very smoothly. I am amazed at the lack of friction even with the gib tightened up. I reckon that the axis could be driven with quite small steppers. I also took the time to make some steel washers for the nut mount screws to stop them grinding their way in to the cast iron.


Next move is to rebuild the X axis and then either mount the X and Y motors or move on to the Z axis. I suspect that I will be impatient and fitted the motors just to see it moving!!

[abfa9358]

X and Y motors on now. I think I'll press on with the Z axis and get all the mechanicals done first before I start with the electronics side of things.

[abfa9358]

It been a while since I last updated this thread, things are progressing if a bit slowly.
First off, my good wife asked for some shelves to be created for the front room - ok cutting and fitting wood is pretty quick its the painting thats slow....

Back to the CNC stuff, I've ordered the Z axis screw and because its preloaded there's a few weeks lead time. This is ok as it give me a chance to work on the control side of things. First off, I've created a custom HAL and pyVCP for EMC2 AXIS to support the mill 3 speed gear box. This was good as it forced me to sit down and get to grips with the HAL configuration and XML.

Now I'm working on the control side, what I'm planning is the fit the D510 motherboard, Mesa cards (7i43 and 7i42TA), the spindle control board and a relay card(home made) in to the existing control box. There appears to be just enough space to do it and with a bit of care and shielding everything should work ok.

I've also taken the head off the column to get at the Z axis lead screw in order to have measure up. It looks like a 25mm ball nut will slot straight in to the existing nut carrier (as indicated in the factory conversion manual), all that's required is to drill/tap six M6 holes for the ball nut - we shall see. One thing that is apparent is that getting the ball screw into the column without covering it in cr*p is going to be difficult, I think I'll protect it with an old bike inner tube. Oh yes, the head weighs a significant amount and may require a counter balance system.

[abfa9358]

The relay card is finished and so the next task is to integrate the new PC and cards in to the exisitng control unit. I'm still waiting for the Z axis ball screw, apparently theres a bit of a delay with machining the ends, no matter theres plenty to do....

[abfa9358]

Bit more progress...
I've got the 7i43 and 7i42 cards mounted into a miniITX case. It all fits in rather well and looks quite neat. I've put in my home made case heater, it switches on a 20W heater coil(square mesh covered box in one of the pics) when the temperature dips below around 10C in the shed. Its enough to keep the PC warm over winter. I'm actually pretty close to moving the X and Y axes as theres not much to do in the driver case to connect everything together.

[digits]

That really is a very nice clean install in that Mini-ITX case!

What do your power electronics live in - is it a 19" rackmount box? I've used the 2U ones from Maplin before, but this time I'm half tempted to go for a steel enclosure with a door that I can get both my Mini-ITX board and the stepper drivers into. I'm not sure if the PC will like all the electrical noise from the steppers though...

Anymore pics, and is it up and running yet?

[abfa9358]

Thank you for your kind comments!
Yep, the power side of things live in a 4U 19" rack mount box shown a few posts ago - its the one where the wiring isn't so neat.

As usual, progress is slow due to work commiments, children's birthday parties, fixing broken toys, painting the cat..... the list goes on.

A few more pictures are added, I've built a simple breakout board to get signals in to the power control box. This card just give me signal + GND pairs and lots of 5V and 12V + GND outlets - all powered by the PC. I also asked around on the UK CNC forum for info regarding soft start circuits for the toriodal transformer as it has a habit of dipping the lights when switched on.

Initially, I was going to use a thermistor but after being directed to this site Soft-Start Circuit For Power Amps and doing a bit of reading, I built the first circuit described in the "control circuits" section. I had to tune the value of R1 from 27K to around 80K to get a 100ms delay on my 12V relay but in the end the circuit seems to work well and unlatches quickly on power loss. I've got 3 x 150R 300W power resistors in parallel to control the surge, these are in circuit for 100ms and then switched out to apply full 240V power to the transformer - I haven't test this side of things yet

I've also got my new motors for the mill - 8Nm on X and Y and 12Nm on the Z, initially I will run these at 45V and their rated 6A parallel current. If necessary I will up rate the transformer to give 70V.

I've also received my gecko drives now and I'm in the process of adding heat sinks to them and finding a cunning way to mount them in the power control box. Its good to see that Gecko have a UK distributor now and can be sourced for sensibly money.

[digits]

I think we may be stepper twins

Have you got any good ideas about limit/home switches for this mill?