Compound Table

[VicParticipant @vic]

I found a video of this table.

[Michael GilliganParticipant @michaelgilligan61133]

Looks like the same old story, Vic

A decent-enough design, let down by the the detailing.

If it does what you want, it’s a very reasonable price

… if you want to improve it ‘as a hobby project, that’s fine

But if you need to improve it, to make it useable …

what price do you put on your time ?

MichaelG.

[VicParticipant @vic]

They sell for between £65 and £130 depending on vendor. At the lower price point it’s definitely worth a few hours of my time – provided I can get it to do what I want. I’ll give it a bit more thought but it looks like it’s worth a go.

[VicParticipant @vic]

Looking at the video again the guy said “the lead screw was reversed”, so he moved the nut to the other side. I’m not sure I understand what he meant by this?  If you look at this part it has a central hole (for the nut on the other side) plus two other holes. The empty one is the original and he has fitted the nut into a new hole he bored. I could ask him what he meant but the video is old and he no longer has the table. He’s also been unable to answer other basic questions due to the elapsed time.

I can’t help wondering if this mod would enable me to swap the table round as the lead screw would be too short otherwise?

Heres the picture.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Vic, I guess that guy had a left hand one, and maybe it was a reject with the hole for the nut being on the wrong side.

Regards Nick.

[Michael GilliganParticipant @michaelgilligan61133]

It’s worth having a look at the comments about that video

… and also his “Mill” conversion that uses the little table.

https://youtu.be/3menFwDDFOI?feature=shared

MichaelG.

[Nicholas Farr]

On Nicholas Farr Said:

Hi Vic, I guess that guy had a left hand one, and maybe it was a reject with the hole for the nut being on the wrong side.

Regards Nick.

Yes, that was my thought.

[MacolmParticipant @macolm]

Having recently got one of these compound slides, here are some observations. It is very much as already indicated, a promising tool, but out of the box spoiled by inadequate features. As supplied there has been no attempt to set up or adjust anything.

The feed screws are threaded  M14x2, one RH and the other LH. Both have a pair of identical ball thrust races, adjusted solely by setting the stiff nut holding on the hand wheel which is also has a parallel key to the shaft. The main problem here is that the inner thrust race merely abuts on the end of the thread, and in consequence is thrown off concentricity. Rotation is therefore not smooth. It should be simple to turn away a short section of the thread and press on a concentric bush. It may also be more stable with a locknut arrangement instead of the stiff nut, making up a special nut with a bigger hex which allows spanner access within the hand wheel recess.

A further problem with the feeds is that the drive nuts are a loose push fit in the central casting, and shift when the direction of rotation is reversed. It looks as if simply fixing in the best position with thread locker will put this right.

Once cleaned of paint! the ways are not bad. The paint softens with cellulose thinners. The gibs are crude, poorly finished, and perhaps not really wide enough for best stability. I am considering milling recesses so that the adjustment screws fit square and do not tend to rock the gibs.

The hand wheels are quite good but the fiducial lines are ragged, the table and T slots are fine, but the fixing slots on the base need cleaned up.

[MacolmParticipant @macolm]

 

Correction of Minor Detail

The thread of the lead screw does not in fact extend to where the thrust bearing seats. The lead screws are made with reasonably good rolled threads, the bar diameter being 12.5mm. Unfortunately the bearing has a chamfer, which rather than its end face, bears against this, and thus may not seat square and not run true. One shaft was all right, the other had a tight zone each turn.

This was fixed by adding a flat washer which ensured concentric contact. I was then able to set up the slides fairly well, slightly easing the dovetails in places with a diamond mini stone to get, for the present, acceptable operation.

Time will tell if it is necessary to do better. The dovetails would need scraping for significantly smoother operation, as well as improved gibs.

[VicParticipant @vic]

Thanks for the additional information. I don’t mind doing some fettling to ensure smooth operation but do you think I would be able to do what I propose in my original post?

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Vic, if the guy in the video did his one, I would’ve thought it should be possible, but it will depend on your own skills. You can always try swapping the table to the other side without the nut in place, to see if it slides okay, but you will have to make sure the hole is in the right place from the opposite side, as it may not be dead centre. The main thing to consider though is, will it mess the whole thing up if you don’t get the new hole in the right place, i.e. will it still go back the right way and work okay if it goes wrong.

Regards Nick.

[VicParticipant @vic]

That’s exactly what I was thinking Nick, thanks for reinforcing my thought process!

I did wonder how the guy in the video might have got that new hole he bored exactly in line. The best I think I could do is to centre the existing hole on my mill as a reference and give it a try.
I suppose if the worst comes to the worst I could end up using the table as it is. Not very convenient but still usable.

[VicParticipant @vic]

The compound in this video is the right way round. I’m not interested in this particular model as it’s made from aluminium and plastic. Interesting though that I’ve not seen it for sale with the same handle orientation as in the video linked.

[Michael GilliganParticipant @michaelgilligan61133]

Good video, Vic

… is that what you are intending to make ?

MichaelG.

[MacolmParticipant @macolm]

The first consideration in swapping the top slide hand wheel to the other end may be which way the table moves for clockwise rotation (ie numbers increasing). On the top slide, the hand wheel is fixed to the table, whereas it is fixed to the base for the lower axis. This means that the top screw is RH thread, and the lower screw LH, both so as clockwise rotation moves the table in the away direction. I think it will be OK, but you should check how this will turn out for whatever change you want.

Both the nuts and the gibs and their adjustment screws are part of the middle block assembly. At a quick look, the dovetail ways are machined central on the other parts, the top slide and the base. So not guaranteed, but the top slide should stay central if reversed. You would still need to drill the hole for the second nut position. The lateral placement would need to be checked carefully, though again I suspect the complete lead screw set up is nominally central on each axis. The options would then be to reverse the slide, or to drill and tap new lead screw mounting holes at the other end of it, possibly decided by which way round gives better smoothness of travel.

 

Further Experience

I have now used the table in earnest to drill 1mm holes in 2mm wide flat conductors in a small electrical cut-out. Precise positioning was very easy. The material had previously work hardened with HSS, but an Ebay carbide drill zoomed through after first making a location pip with a diamond point.

The remaining issue is that the top slide is stiffer in one direction, and this is due to the nut taking up different sideways positions. Rather than to locktite the nuts in place, I have decided to drill and tap holes for clamp screws. These need to go in the centre block and parallel to the lead screws. To make up the length and avoid marking the nuts, I expect to use small brass rods under the clamp screws.

[Michael Gilligan]

On Michael Gilligan Said:

Good video, Vic

… is that what you are intending to make ?

MichaelG.

Something like it yes. I have a boring head already, and I may be able to substitute my spin indexer for the rotary table. If not I’ll buy one. The one in the video is only a small 3” one so pretty cheap. Even some 4” ones aren’t expensive if it will fit, which it should.

[Macolm]

On Macolm Said:

“The first consideration in swapping the top slide hand wheel to the other end may be which way the table moves for clockwise rotation (ie numbers increasing). On the top slide, the hand wheel is fixed to the table, whereas it is fixed to the base for the lower axis. This means that the top screw is RH thread, and the lower screw LH, both so as clockwise rotation moves the table in the away direction. I think it will be OK, but you should check how this will turn out for whatever change you want.”

Thanks for the explanation Malcolm, I’ve been trying to get my head round this!

I think I will get one next month when my credit card recovers. 😉

[VicParticipant @vic]

If it’s of any interest to anyone else, this guy has done a whole series on the subject.

[Vic]

On Vic Said:

 

I did wonder how the guy in the video might have got that new hole he bored exactly in line.

Do the job in a way that does not require precise alignment. Or, to put it another way, let the table screw determine final alignment of the nut. Make a bigger hole in roughly the correct place, wax the nut, put some JB Weld in the hole, put the nut in the hole, screw the upper slide back on. Leave until the JB Weld sets. The screw will align the nut up and down, left and right and rotationally in plan. If the JB weld is a bit thicker on one side of the annulus than on the other, who cares?

It would be a little bit like how they fixed railings into stonework with lead – drill the hole near enough, put in the railing and then pour in the lead.

[VicParticipant @vic]

As I’d decided this compound table is quite small I’ve been looking at alternatives but not found anything with the right size/price point to fit the bill. Many are just too large in one direction or other. I’ve concluded that this unit should be suitable if I can make a bigger table for it, possibly with a longer feed screw as well. it’s difficult though to see exactly what can be done without actually having the unit in front of me so I’ve ordered one from eBay for £63.59, fingers crossed it’s no worse than some of those I’ve seen in some YouTube videos.

[Macolm]

On Macolm Said:

 

Further Experience

I have now used the table in earnest to drill 1mm holes in 2mm wide flat conductors in a small electrical cut-out. Precise positioning was very easy. The material had previously work hardened with HSS, but an Ebay carbide drill zoomed through after first making a location pip with a diamond point.

The remaining issue is that the top slide is stiffer in one direction, and this is due to the nut taking up different sideways positions. Rather than to locktite the nuts in place, I have decided to drill and tap holes for clamp screws. These need to go in the centre block and parallel to the lead screws. To make up the length and avoid marking the nuts, I expect to use small brass rods under the clamp screws.

I wouldn’t mind seeing some pictures of this when you get round to it.

[VicParticipant @vic]

As a brief postscript, I bought one of the tables and as expected it was a bit rough in places. After a small amount of remedial work I’ve otherwise been able to use it as supplied. It works reasonably well for my purpose.

[Author]

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