Mark Davison
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What size ball screw is that, 1605?
- Thread starter Fastdruid
- Start date
Yeah, I'd already "removed" the ball when I stuck a slot in it with the angle grinder. I then flattened it off before trying to drill it. Just wasn't having any of it.
Yep, Y is a 1605, Z and X are 2505.
I could probably have gone a bit smaller on the X and bigger on the Z. It is however fairly straightforward to replace the Z if need be.
Mark Davison
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I fitted a 2005 on the X, was very tempted with a 3205 on the y but cost drove me to the 2505 in the end.
I presume you mean a 2505 on the Z! A 2505 on the Y!
It wouldn't even fit through the hole in the front of the knee, let alone there be any knee left if you cut it away for even the smallest of nuts to fit! Although it's "smooth" there is a significant amount of "staining" on the pivot section.
Any suggestions on how best to bring it back to looking nice _without_ affecting what is a reasonable precision surface?
A bit of a clean up later...
The original top photo is bottom right in this one, the bottom photo is top left.
Bit more progress.
Marked, drilled and tapped 5/6 of the holes to mount the ballnut. Haven't done the 6th yet as it appears I double marked it and I wasn't entirely sure which one was correct. I've re-marked it properly now and I'll drill and tap in due course.
Also found out that the webs on the underside of the table are varying depths, the ballnut mounting plate would only let it travel about 2/3rds before it hit on one (I'd tested it at one end rather than over the entire travel). So I ground a bit more off and now it clears fine.
(bolts used are "random" ones that were close to hand rather than the ones I'll be using hence why they stick out so far!)
It now "moves" nicely from one side to the other, except for the "lost" travel at the ends.
Not sure here if it's worth spacing out the end plate or just live with the loss of the ~16mm of missing travel. I suppose I could drill the end plate for the ball nut plate mounting bolts which would bring it down to 8mm.
Equally the bearing block very slightly overlaps into the base on the other side, enough to lose ~10mm or so.
I'm loath to take that off the centre so again I'd probably space it out rather than anything else.
Marked, drilled and tapped 5/6 of the holes to mount the ballnut. Haven't done the 6th yet as it appears I double marked it and I wasn't entirely sure which one was correct. I've re-marked it properly now and I'll drill and tap in due course.
Also found out that the webs on the underside of the table are varying depths, the ballnut mounting plate would only let it travel about 2/3rds before it hit on one (I'd tested it at one end rather than over the entire travel). So I ground a bit more off and now it clears fine.
(bolts used are "random" ones that were close to hand rather than the ones I'll be using hence why they stick out so far!)
It now "moves" nicely from one side to the other, except for the "lost" travel at the ends.
Not sure here if it's worth spacing out the end plate or just live with the loss of the ~16mm of missing travel. I suppose I could drill the end plate for the ball nut plate mounting bolts which would bring it down to 8mm.
Equally the bearing block very slightly overlaps into the base on the other side, enough to lose ~10mm or so.
I'm loath to take that off the centre so again I'd probably space it out rather than anything else.
Finished off mounting the ball nut, all holes drilled and tapped now. This is the other side.
After having a think about things I drilled a couple of holes in the RHS mount
This let me bring down the "lost" travel to 8mm on that side
I don't think I'm going to touch the left side tbh. It does mean 10mm one side and 8mm the other but I can live with that. According to the manual originally it would have been 380mm of travel and I calculate (if my measurements are correct!) I'll actually end up with 400mm so the "loss" of 16mm isn't actually a loss anyway.
After having a think about things I drilled a couple of holes in the RHS mount
This let me bring down the "lost" travel to 8mm on that side
I don't think I'm going to touch the left side tbh. It does mean 10mm one side and 8mm the other but I can live with that. According to the manual originally it would have been 380mm of travel and I calculate (if my measurements are correct!) I'll actually end up with 400mm so the "loss" of 16mm isn't actually a loss anyway.
So, an evening of fun later and I have this.
Now I didn't _intend_ to trial fit it...but the nut was on the shaft the wrong way anyway so...
Now I do need to do a bit of cleanup still, when I take the knee off I'll be getting the powerfile out and cleaning the channel up, there are casting lumps that make absolutely no difference normally but I'm _so_ close on clearance that it's hitting and it causes problems.
Nothing more than a cleanup though, I'm not removing any more than the lumps and bumps. Equally I need to take a bit more off the bottom still.
So, after this I realised there was something odd going on. The nut ran fine down the channel, my model said I had plenty of space but when fitted altogether the nut was hitting the "side" of the channel and lifting the carriage.
After looking some more I realised that I'd made a strategic error. I'd relied on Andy's 3D model and just checked some critical dimensions. One of them being the width (and depth) of the nut channel. Where I went wrong is the casting on mine is "off", the channel is about 1mm off centre and because it's just not a critical part (there is plenty of room for the bronze nut) it's not been corrected in machining.
If you look at the picture above you can kind of see by eye that the left side is narrower than the right side (by ~2mm).
In hindsight looking from the other side you can see it in the thickness of the casting as well, it's noticeably thinner on one side than the other (thinner on the right now because we're looking from "behind").
Now if I'd realised this earlier I could possibly have shifted things over by 1mm but to do it now means a new ball nut, new ball nut carrier and new bearing block holder... So despite saying I wouldn't, instead I broke out the router....and then because I didn't have enough clearance on the mill I took off the knee as well.
I've still got a bit of clean up to do but it's now central, should be plenty of clearance and still have plenty of metal there as well.
You can also see here the difference in the pocket "floor" depth, I went all over it with the router at the same height, it's taken about 1/2" mm out of the bottom (in the image) but hasn't touched most of the top.
Mark Davison
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Mine wasn't central either. I didnt have to remove much material to get the ball nut carrier in, but I'm glad I'd bought the die grinder!
I thought I could get away with little more than a cleanup. C'est la vie.
Anyway, assembled Y on the bench as it stands. Not the easiest of things to assemble like this as it's a bloody heavy thing.
Winds up and down nicely, it will spin down under its own weight with just the ballscrew but won't with the motor connected even unpowered.
I need to add a brace to the motor mounting plate as there is far too much flex in there. I always knew I would but until it was all in place I wasn't exactly sure how best to do it.
I can however build a test rig (if I can find my code I wrote for the arduino when I played with it before) to drive the motor and try it out properly.
Many hours of digging my test code out (which doesn't work very well[1]) and wiring things up and we have another scintillating action video....Only this time powered!
(it's slightly less dull than the last video but still 36 seconds of your life you won't get back).
It works!
[1] I'm using an MPG on it and it's not consistently reading it and so not generating pulses. I'm not sure if it has too much going on and can't read it fast enough, it's interference, it's just badly coded...or I'm using the wrong version and I fixed this issue when I last played with it about four years ago!
Turns out it's badly coded!
Reads the MPG fine, doesn't consistently turn that into pulses. I'll have more of a play with it as I can theoretically use it to control things before I've _actually_ got the proper control system up and running.
Reads the MPG fine, doesn't consistently turn that into pulses. I'll have more of a play with it as I can theoretically use it to control things before I've _actually_ got the proper control system up and running.
Next up we have a re-visitation of the Z. Originally I was going to use a clamp between the stub shaft and the ballscrew. A bit of a consideration however and I realised that I was losing some Z travel because things bottomed out.
I had originally planned to live with it but then changed my mind. To fix it though I needed a new stub shaft.
Start off with one 40mm piece of bar...
Turn it down to 17mm'ish
Then cut an M17x1.0 thread, turn the end down to 14mm, stick a relief in the middle, cut a spacer for the bearing and clearance for the cup... then reverse it, clock it in the 4-jaw and bore a 20mm hole.
In the end we have this.
In comparison to my previous version.
I do have a bit of work left on it, I need to cut a keyway[1] and drill and tap two holes to hold the ballscrew in place (it's a "D" so a pair of bolts will hold it very nicely.)
All in I gain probably about 40mm. That's not 40mm of extra Z btw, I've only "gained" about 10-15mm of additional Z but it means I can have a cover over the ball nut and not have that being the "end stop".
[1] X and Y I'm not bothering but Z has a *lot* of weight on it even when not doing anything.
I had originally planned to live with it but then changed my mind. To fix it though I needed a new stub shaft.
Start off with one 40mm piece of bar...
Turn it down to 17mm'ish
Then cut an M17x1.0 thread, turn the end down to 14mm, stick a relief in the middle, cut a spacer for the bearing and clearance for the cup... then reverse it, clock it in the 4-jaw and bore a 20mm hole.
In the end we have this.
In comparison to my previous version.
I do have a bit of work left on it, I need to cut a keyway[1] and drill and tap two holes to hold the ballscrew in place (it's a "D" so a pair of bolts will hold it very nicely.)
All in I gain probably about 40mm. That's not 40mm of extra Z btw, I've only "gained" about 10-15mm of additional Z but it means I can have a cover over the ball nut and not have that being the "end stop".
[1] X and Y I'm not bothering but Z has a *lot* of weight on it even when not doing anything.
Rather than rebuild the mill just to cut a keyway I did it in the lathe using the (broken!) vertical slide.
For some things like this it's actually easier anyway in the lathe because of the V cut in the slide it is trivial to centre things (pop in a dead centre, line it up to the centre of the V).
I cut the keyway and drilled the two holes for locking the ballscrew shaft on.
I was particularly happy with the keyway. Actually, no, I'm *really* happy with how the entire thing has come out. If I'm being critical I really should have stuck in a bull nose tool or round (or even used a combination of left and right tools) to take out the relief so that it's not got a nice slope one end and a hard ridge the other. But that's a really minor thing and will be buried deep in the knee anyway!
The line at the top there is because my live centre got in the way of the "first" 5mm of so of the cut and it flexed enough to be too large to slide the taper lock bush over while perfectly sized further down, I just took an extra cut to clean that first bit because it'll be cut off later anyway.
Next up is a trial fit, mark where the pulley comes to and then chop the excess of the shaft. Then I can actually assemble everything.
Scarily close now to having a working CNC mill!
For some things like this it's actually easier anyway in the lathe because of the V cut in the slide it is trivial to centre things (pop in a dead centre, line it up to the centre of the V).
I cut the keyway and drilled the two holes for locking the ballscrew shaft on.
I was particularly happy with the keyway. Actually, no, I'm *really* happy with how the entire thing has come out. If I'm being critical I really should have stuck in a bull nose tool or round (or even used a combination of left and right tools) to take out the relief so that it's not got a nice slope one end and a hard ridge the other. But that's a really minor thing and will be buried deep in the knee anyway!
The line at the top there is because my live centre got in the way of the "first" 5mm of so of the cut and it flexed enough to be too large to slide the taper lock bush over while perfectly sized further down, I just took an extra cut to clean that first bit because it'll be cut off later anyway.
Next up is a trial fit, mark where the pulley comes to and then chop the excess of the shaft. Then I can actually assemble everything.
Scarily close now to having a working CNC mill!
Carl Wilson
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I'm not 100% certain mine is 1968. I also don't know if there are shims in my Z axis guide or not, haven't had it apart yet.
With regard to the lubrication nipples, I had some broken 90 degree ones on the saddle. They perplexed me for a while until I realised they had been press fitted in. To remove them I cut off the 90 portion with an air powered die grinder mounted with a small cutting disc. Then I carefully drilled out the core of the fitting until only a thin shell remained. Rotating this with an easy out brought it out without issue.
What is the serial?
You can easily tell by looking at the front of it. If it has this kind of style bolts with a castle type ring round the cap screw then it has the adjusters in.
I'm not entirely sure however how it actually adjusts, if it has shims in or just varies how tight the rear strips are clamped on.
If the rear strips are attached with _just_ cap screw bolts (like mine) then it has no adjusters and you'd have to take material off the mounting face of the rear strips to tighten it up. Although actually I think it would probably be better to add a turcite strip and if need be add some shims. It would of course depend on where the wear was.
Minor update. Would have been more of one...but Windows Update broke my PC and so I've spent many hours trying to fix it instead.
Anyway, moving closer to re-assembly figured I'd sort out some lubrication. Firstly for the Z stub I drilled and then tapped a hole into the motor/bearing mounting plate.
This should drip oil down, through the bearing, down the shaft and then into the lower bearing...Probably. Clearance _might_ be a little close between the bearing and the mounting "shell" but we'll see.
To ensure I didn't fill the knee up with oil over time (although I guess there are worse things) I drilled a drainage hole in the bottom.
That should ensure this area doesn't fill up with liquid (might be oil, might be coolant). I did remove a whole bunch of crap from here so I'm pretty sure it filled up in the past.
Next up was the Y, for this I'll use the existing oil "route" which runs to above the Y "nut", if you look *really* closely you can see the dark spot that is the oil port in the side of the centre hole.
Originally this dripped on top of the nut mount and then there was a hole through from the top to the inside of the nut, instead I created a flat down the side of the mounting section of the nut and a groove into the "oil" port on the ballnut.
Turns out after testing that this will _also_ drip onto the ballscrew itself ahead of the ballnut. Which I'm fine with.
That's pretty much it. Oh except for this which I did ages ago but hadn't pictured before. Eccentric for the belt tensioner.
Anyway, moving closer to re-assembly figured I'd sort out some lubrication. Firstly for the Z stub I drilled and then tapped a hole into the motor/bearing mounting plate.
This should drip oil down, through the bearing, down the shaft and then into the lower bearing...Probably. Clearance _might_ be a little close between the bearing and the mounting "shell" but we'll see.
To ensure I didn't fill the knee up with oil over time (although I guess there are worse things) I drilled a drainage hole in the bottom.
That should ensure this area doesn't fill up with liquid (might be oil, might be coolant). I did remove a whole bunch of crap from here so I'm pretty sure it filled up in the past.
Next up was the Y, for this I'll use the existing oil "route" which runs to above the Y "nut", if you look *really* closely you can see the dark spot that is the oil port in the side of the centre hole.
Originally this dripped on top of the nut mount and then there was a hole through from the top to the inside of the nut, instead I created a flat down the side of the mounting section of the nut and a groove into the "oil" port on the ballnut.
Turns out after testing that this will _also_ drip onto the ballscrew itself ahead of the ballnut. Which I'm fine with.
That's pretty much it. Oh except for this which I did ages ago but hadn't pictured before. Eccentric for the belt tensioner.
Carl Wilson
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- Moray
Mine isn't like that, it has two locking bolts, which I assume are bigger versions of the saddle one which I made a replacement for. They have short handles on them to lock the Z. To be honest, I don't think that there is a huge amount of wear in it.
Ah, yours is like mine then (except I'm missing the handles, I just have a nut on one side). I probably should try and make some new ones, particularly as when it's un-powered I think it may roll down under its own weight.
