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The R-8 Spindle is longer below the head than the MT3 spindle and the 1.75 sounds about right. I thought the standard R-8 drawbar was something like 7/16x20.
Alan
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Below is a picture of a used R-8 X2 head I picked up recently. The spindle sticks out nearly 1.75" from the bottom face of the head. My MT-3 spindle only sticks out around 0.85". The near extra inch on the R-8 is a lot of travel to give up on a little machine. The R-8 spindle dimensions agree with a drawing available at littlemachineshop but the whole thing assembled disagrees with most published X2 photos? The spindle appears to protrude the correct amount fron the top of the head. If this spindle is some variant I am not impressed
The other oddity is the coarse thread draw bar that was included.
Anyone who says "It only goes together one way" has no imagination.
The R-8 Spindle is longer below the head than the MT3 spindle and the 1.75 sounds about right. I thought the standard R-8 drawbar was something like 7/16x20.
Alan
Well that would solve the mystery. I was comparing to pictures on web pages which are a little tough to measure with a ruler.Originally Posted by acondit
You thought right. I'm using a piece of 7/16-20 threaded rod as a temporary solution.I thought the standard R-8 drawbar was something like 7/16x20.
The use of MT3 has an upside after all.
Anyone who says "It only goes together one way" has no imagination.
1.65" on my R8 spindle.
7/16-20 drawbar thread.
Drawbar to collet engagement is about 1/2".
Sounds right. My measurement was done with a tape measure.
Follow up question.
2 heads. One MT3 with the original gear drive. Other R-8 with Ron Steele belt drive.
Which one to use as a lathe mounted to the mill table ? One thought is the shorter spindle of the MT3 might offer some advantage. I plan to do simple turning jobs on small diameter round stock held by collets. Might want to add a chuck eventually although how to safely mount a chuck is a bit unclear atm. The belt drive can be moved to the MT3 head if necessary.
Edit/ The motor on the new/used head has been dismantled. Where do the thin wavey washer/shims go ?
Last edited by cyclestart; 08-04-2008 at 03:43 PM. Reason: need more info
Anyone who says "It only goes together one way" has no imagination.
I'd vote for the MT3 head. My lathe (9x20) has an MT3 taper in the spindle.
They do make small chucks that mount on a taper or even R8. You could even buy a miniLathe spindle from LMS.
Take a look at the manual for the washer/shims.
Alan
Cyclestart,
Take a look at this thread message 21. R8-Chuck.
Alan
The X2 spindle housing is the same basic part as the 7x headstock. You can buy a lathe spindle from LMS for $30 as of a week or so ago and mount it in the same bearings. What I like about this is it will make it easy to swap chucks between my 4th axis and my lathe.
One thing I like about the R8 taper is that in the US at least it's super easy to find pretty much anything you want to fit it. Also I like that it is not a sticking taper when it comes time to change tools. Small beans but it's something. Either one will do the job!
Finally found time to play a little.
The raw materials
1) Spare X2 head
2) one chunk .375" shaft
3) broken tap held in scrap piece of aluminum
4) a rainy day
Had so much fun that the next step is a proper lathe spindle (w/chuck), tailstock, and threading ability. For threading I hope to use emc's ability to do the counting on the software side. Will need to seek some help on that without doubt. Would this be considered sort of a "generic" all-purpose encoder?
http://www.usdigital.com/products/en...rotary/kit/e2/
Not sure what kind of part this is, possibly one end of a rolling pin? Picture attached in any case.
Edit\ encoders seen on ebay often look designed to fit on motor shafts. Is there another style for spindles? Admitted electronic idiot here.
Anyone who says "It only goes together one way" has no imagination.
This is a really interesting project. I have an extra head too and am interested in some kind of 4th axis/lathe concept like this.
I haven't run it but according to the EMC2 docs, all you need for threading is a 1 pulse/rotation encoder, which is easy enough to DIY. It's basically the same as a home switch. The most common method seems to be to use an optical switch or a Hall Effect sensor which picks up magnetic fields and stick a magnet somewhere on the whole thing. Either way you use a simple circuit like a comparator to make sure you generate clear and repeatable ON/OFF states.
Just a few items.
If you are going to get the lathe spindle, you will need two of the same type bearings. The size that fits the top of the R-8. The one around the r-8 collet has a larger hole because the shaft is larger. I just dismantled my spare minutes ago to powder coat and then use on my new lathe project. You may or may not want the end spacer, but the mini lathe spindle comes with two of the spanner locking nuts on the end when store bought. Not sure why that is either. You will have to order all the parts you want separately. Between those would be a good spot to mount a disk with a hole in it for one of these.
http://www.cnc4pc.com/Store/osc/prod...roducts_id=129
I bought one and that is my intended location for the disk. Just mount the little pickup fork on a plate on top of the head.
Once I get my lathe completed, I will then have my mini lathe spindle that I could mount on the mill or router for play stuff. 4 axes are just plain cool.
From some further reading it looks like a ~200 count encoder with index is the preferred emc way. Could be wrongI need to learn about encoders for another project in any case. Expect this will be a steep learning curve for an electronphobic.
Ugh! Changing bearings? Maybe I'll just buy the whole head assembly from LMS. Can never have too many spare parts
Anyone who says "It only goes together one way" has no imagination.
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