Can’t find what I’m looking for!

[Peter G. ShawParticipant @peterg-shaw75338]

[Peter G. ShawParticipant @peterg-shaw75338]

Hi all,

 

I’m in the process of  re-building my Warco MiniMill (at long last – don’t ask!) and am trying to add some improvements as I go along.

 

One such improvement is to clean up the dovetails as per David White with his X1 mill – and by heck they need doing. Eg, the visible slides of the column were reasonably, but the invisible slides on the matching part looked as if they had been roughly ground down with an angle grinder. Anyway, next step is to add some more gib adjusting screws, a new gib strip, and some small balls between the screws and the gib strip.

 

Now, Circlip recommends a slot in the gib strip. But I think that somewhere I’ve seen something about using a V shaped slot as done on the Myfords which perhaps seems rather better than Circlips presumably rectangular slot. But can I find it? Can I heck!

 

I’ve been back as far as MEW 138 (Feb 2008) looking in Scribe a Line. I’ve scoured any thread that might seem appropriate on these forums, nothing doing. So does anyone have any idea about this? Is my memory correct? Or is it a figment of my imagination? If the latter, then fair enough, I won’t object if someone tells me that, but please, someone put my mind at rest.

 

Regards,

 

Peter G. Shaw

[mgjParticipant @mgj]

Peter- when you say a slot in the gib strip…. where is that?

 

The gib housing  slot may be cut with a vee shaped dovetail cutter, and some gibs are flat.

 

These grooves are to take the ball bearings and stop them skidding on the gib (and positively locate the gib)? If so a dimple will be fine. Better if it was a proper radius dimple made with a ball ended slot drill of the right diameter. Better still pin and dimples.

 

The Myford gib strips from memory don’t have grooves or slots in them.

[CirclipParticipant @circlip]

Hi Peter, NOT a reccomendation but an observation of how the problem of locking the cross slide was solved by the illustrious designers of my own rotary scrap generator.

 

  The Gib strips on my own machine  are trapezoidal in cross section and are tensioned by cross slotted pointy screws with locknuts on them. It would still apply to one with a single angled face.

 

  The slide lock in my case is a Cap screw with a dimple in the end which locates a single ball bearing the diameter of which is slightly less than the root diameter of screw.

 

  What the manufacturers have then done is cut a square sided channel about 1mm deep ACROSS the face of the strip, which if the adjusting screws were removed, would still be retained longitudinally when screwing the cross slide in and out.

 

  The point about the ball being in a slot means that the strip is free to slide into the top corner of the vee when wearing.

 

  The problem with the dimple, and please DON’T take this as a personal criticism Meyrik, is that it holds the strip on a point contact against the tapered face, same applies to the soft rod with an angled face “Slug” sometimes used.

 

  You got three options Peter, choose whichever (Or your own concoction) you feel happy with.

 

  Regards Ian.

[Peter G. ShawParticipant @peterg-shaw75338]

First of all, the gib strips I have seen have all been the same design, ie a rectangular bar with chamfers on two diagonally opposite corners. I’m saying this to be absolutely certain of what we are talking about. In addition, the adjustment screws all seem to bear on a “hole” partially drilled in said strip.

 

Now, on one machine, possibly the Hobbymat but can’t be sure, there was a transverse diagonal groove into which one of the adjustment screws located. Also, I had a suspicion that the Myfords used the same idea.

 

On my present machine, the dimples for the screws are rough, dead rough. And I’m not too sure how accurately located they are in respect of the position of the adjustment screws, which themselves are Allen head grubscrew types with a squared off end . The gib strip itself is somewhat rough. So the intention is to replace both the gib strip and the screws with better fitting items. And this where the idea of the transverse slot or groove comes in. Incidently, although there is a locking screw, it does not have anything to locate in.

 

Reading Circlips message above, I’m now thinking I may have misunderstood the purpose of the slot or groove in that it seems that it may be a device to assist in locking of the slide. This does make more sense to me because on the one I remember, there was just the one groove, but I can’t remember whether it was for locking or not. It would make sense for it to be locking because the groove would make a weaker point which would then bend easier.

 

 Your comment on the ball bearing size does make a lot of sense since the original article I read used a 2mm diam ball, whereas my slides use 6mm screws, hence I would have thought that perhaps a 4 or even 5 mm diameter ball would have been better. 

 

 I don’t have a ball ended cutter so would have to make do with a drill point. Mind you, I could write off a drill bit and round it off!

 

Ok, I think that initially reassembly with existing items is on the cards, followed by replacement with better stuff.

 

Regards,

 

Peter

[mgjParticipant @mgj]

Circlip – that’s quite right – I can see that. And it makes sense. The only thing against it is the amount of wear fro which one is compensating?

 

The dimple does create a point contact and a weak spot in the strip. Possibly the answer to that one is to make the dimple less than the OD of the ball – to get contact only on the circumference of the dimple, which would spread the load. And that would be better.

 

Its as broad as it is long I guess, for any of them – for us as model engineers where machines are not coping with continuous hours on production.

 

Peter- your strips with bevelled top and bottom edges are Circlips trapezoids.

 

IMO the BEST gibs are the long tapered gibs, and you have a screw at each end, to push it in or push it out. Whether they are better (more effective)than the Myford strip type I don’t know, but they are certainly much easier to adjust.

[CirclipParticipant @circlip]

You’ve mentioned the originators Peter, the HobbyMat was a later product of EMCO the company that made my MaxiMat. so if it worked before for them??

 

    Reards  Ian.

[Michael GrayParticipant @michaelgray16785]

Meyrick, totally agree with you “IMO the BEST gibs are the long tapered gibs, and you have a screw at each end, to push it in or push it out.”

And the lathe I bought from the local High School had just that – unfortunately some little twit(s) had unscrewed one end and not moved the other screw appropriately!  Sheared off the metal between the slot which captured the head of the screw and the end of the gib and left too much slop with only one adjustment.

Got it to a place I could work with and left it, it’s still working well for the friend I sold it to when we moved into an apartment – not too much space for a 12 x 24 Lantaine, nor a strong enough floor I’d bet.

regards,  Mike

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