Ancient Knee mill retrofit

[kong]

After the y-axis, it was simple job to hook up the x-axis screw. Unfortunately, I had to butcher the nut-retaining block a bit (it started off as a cuboid) so it would fit under the table, but again, it is still fully functional and holds the nuts securely in place. Could have done with a milling machine here, but the bandsaw and lathe were put to good use. Just got to give it a lick of paint on the table now, then it will be on to the tricky z-axis.

[kong]

Almost finnished the z-axis nut carrier now, so here it is so far. Essentially it is a spindle with the two ballnuts trapped inside so when it is spun, the ballscrew will move, hopefully taking the milling spindle with it. The first few pictures show the insides - a bored cylinder to trap the nuts and hold the bearings on. I managed to drill the clearance holes for the ball-returns on the rotary table. If I never had that, I guess it would have been a file job since the piece was too big to offset in the lathe. This part is made from 2.5" dia 2024 aluminium since that was what I had on hand.

[kong]

The last two shots in the previous post show the bearing holder. 4" aluminium bored to just clear the spindle, then bored each end to hold the bearings. A hat on each end keeps everything locked together, and there is just enough room on the end to get that pulley on!

Last job for this part will be to turn a flat section on the whole assembly and mount it to the miller on the round plate shown in the last photo. i ahve really had enough for one day though, so it wil have to wait!
Oh yeah, don't be scared to comment guys, it is nice to know there are people interested in this!

[Bloy2004]

Hi Kong
I'm watching with interest!

[DieGuy]

Keep going! nice so far!

[balsaman]

Amazing. What sort of propulsion will be employed?

Eric

[kong]

Thanks guys, always nice to know what people think

Eric, I have 2 servo motors so far, almost the same as yours. All I know about them is they are 48v, but are similar in size to the ones you used so hopefully they will be ok. The thrid motor is proving difficult to find, we just don't have the suppliers over here unless you want to pay top dollar. There is one on ebay I am watching at the moment - http://cgi.ebay.co.uk/ws/eBayISAPI.d...sPageName=WDVW which looks like it should be suitable. Otherwise I am constantly watching ebay, and ebay.de too. The geckos are on order and should be here shortly.
I am gonna go to the metal shop tomorrow and pick up a steel plate to connect the z ballscrew to the spindle. I am thinking somewhere around 3/4" thick should be acceptable, but there will be around 4-6" between the spindle and screw, so I must be certain it won't flex under a heavy cut.

[Al_The_Man]

There is one on ebay I am watching at the moment - http://cgi.ebay.co.uk/ws/eBayISAPI.d...sPageName=WDVW

Are you are aware that motor has a wound field? and as such will require a Field supply and open-circuit field monitoring.
Al.

[kong]

Nope, it didn't even click! Not to worry, I haven't bid on it so nothing is lost. Just gotta kep searching. Thanks Al.

[kong]

What about this one then - http://www.distel.co.uk/asps/details1.asp?ID=TE18
Althiugh I only have a 48v power supply, so I guess I will lose some speed, the spec states 1485 rpm at 48v. How will this effect the torque of the motor? I guess I really should take some time to learn this stuff eh?!

[Al_The_Man]

I am not sure how that armature is connected with three wires for fwd/rev, unless they have some odd armature configuration? I would think that would limit it somewhat compared to a DC servo amp that will do the reversing automatically. I would get alot more information before picking that up.
Al.

[kong]

Thanks Al, I phoned the guy today, and he assures me it will work with Gecko drives, as long as I use diodes on the lines. Bottom line is, I have little choice at present, so I will go with it. As soon as the geckos turn up, I will give it a go. If it doesn't work, he will be getting it back.....watch this space!

On with the z-axis. I managed to get a flat milled on the cylinder, unfortunately it was too big to turn on the lathe, but luckily my father has just taken delivery of a Sieg X3 mill, so I shot over there and used his mill. Thanks dad
The steel plate was a bigger problem, since it was also too big for the lathe, and I needed to cut a 4" diameter hole. I ended up drilling a series of holes around the circumference which let the centre slug drop out (well, with a couple of blows from the persuader of course).
The other problem was mounting onto the spindle - If I used a clamping method, I would have lost 20mm of travel, and since I only have 4" anyways, I had to drill/tap holes in the underside of the quill and bolt it on that way.
All mocked up for now, I will take it apart again tomorrow now I know it all works, and tidy up the plate a bit on the bandsaw. Here what I got for now...