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Intended function of gib screws

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Bill Phinn17/01/2019 18:47:01
185 forum posts
35 photos

I recently bought a cross slide vice for my bench drill from a certain Devon-based tool retailer.

One of the selling points was that in addition to having “adjustable gibs” it had “lockable slides” (these two features were individually highlighted in separate bullet points in the item’s description).

I was disappointed when the vice arrived to see that it didn’t have lockable slides though it did have adjustable gibs. When I queried the absence of lockable slides with the retailer, I was told “in order to lock the slides you tighten down the gibs”.

It had taken me some time to do the adjustment of the six gib screws in order to end up with both an absence of any slop and very smooth travel along the full length of both axes. Do I really want to be messing with the spot-on adjustment of even one or two gib screws virtually every time I use the drill?

I’d be interested to know what others make of the retailer suggesting that gib screws are a routine way of locking slideways, and also the retailer’s apparent claim that, in spite of “adjustable gibs” and “lockable slides” being mentioned in separate bullet points, what the buyer should understand this to mean is that firstly the gib screws can be adjusted, and secondly they can be adjusted all the way down on to the gib strip!

cross vice.jpg

Edited By Bill Phinn on 17/01/2019 19:14:41

Michael Gilligan17/01/2019 18:51:06
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13547 forum posts
586 photos
Posted by Bill Phinn on 17/01/2019 18:47:01:

I’d be interested to know what others make of the retailer suggesting that gib screws are a routine way of locking slideways, and also the retailer’s apparent claim that, in spite of “adjustable gibs” and “lockable slides” being mentioned in separate bullet points, what the buyer should understand this to mean is that firstly the gib screws be adjusted, and secondly they can be adjusted all the way down on to the gib strip!

.

Bovine manure

MichaelG.

Mike Poole17/01/2019 18:54:07
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2012 forum posts
46 photos

I think I would drill and tap for one or two Kip type locking handles so you don’t lose the setup of the gib strip. Depends how far you feel you should go to put right the sellers misselling.

Mike

Clive Foster17/01/2019 19:07:46
1776 forum posts
57 photos

#2 for Michael Gs' short and to the point comment.

Any self respecting cross vice needs axis lock screws. Rule 1 when drilling is line up and lock the axes so the job stays put when cutting. Even my ancient and distinctly Early Chinee Sloppy 6" version bought from a Model Engineer exhibition many, many years ago shortly after they first hit the market has locks. Not good locks but they work just well enough that there has never been quite enough impetus to translate the desire to make better into action. Currently sitting on my Fredr'k Pollard 15AY drill. A seriously industrial MT 3 machine which definitely tests their effectiveness with big drills.

Having lived with my sloppy one for mumble mumble years I'd say good locks are more important than good gib adjustment or tight feed screws. Attempting to runa big drill on mine without locks is a bit scary as things go every which way quite significantly until the drill reaches full diameter.

Using an over tight gib screw to lock the slide is a good way to distort the gib. Especially if ordinary pointed screws are used. Proper locks should operate via a relatively large diameter pusher to apply force over a reasonable flat area.

Frankly trade descriptions act applies.

Clive.

Edited By Clive Foster on 17/01/2019 19:08:36

Bill Phinn17/01/2019 19:08:10
185 forum posts
35 photos

Many thanks, Michael and Mike.

Mike, I emailed the retailer yesterday afternoon and said exactly what you suggest: that if I keep the vice I would probably want to drill and tap for two locking screws. I also said I wasn't too happy at the somewhat misleading description.

I haven't had a reply yet.

 

ETA: Many thanks, Clive.

Edited By Bill Phinn on 17/01/2019 19:09:02

Clive Foster17/01/2019 19:19:23
1776 forum posts
57 photos

Think a Kipp / Bristol style handle as suggested by Mike may be overkill. My locks have simple oval flat head thumb screws maybe 3/4" and a bit across working via some coarse Chinee thread sort of 1/4" diameter. I think a similar device with a fine thread of similar diameter would be more than satisfactory.

Has the advantage that you can ensure there is always clearance. I've broken my share of Kipp / Bristol handles and bent the odd tommy bar simply through forgetting that they were in the way when adjusting something and neglecting to adjust them out of harms way.

Clive.

Fowlers Fury17/01/2019 21:35:14
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323 forum posts
72 photos

" I've broken my share of Kipp / Bristol handles and bent the odd ........ "
Likewise Clive ~~~~ repeatedly on the mill !

Some years ago I purchased a similar vice to that of the OP (Bill Phinn) for fitting to the table of the Startrite drill press. I hope his version is better than mine although that one did have single "locking" screws on each slide. After a while it was gladly taken to the club auction night. The amount of backlash with the screws was hopeless as were the graduations on the handles. The "locking" screws didn't hold when drilling > 1/4"D holes.

If Bill does "want to drill and tap for two locking screws" then I'd suggest inserting dowels at the same time as recommended by Geo Thomas. His write-up on gibs and their behaviour in The Model Engineers Workshop Manual is worth reading. I followed his guidance for fitting a lock and dowel to the top slide of my S7 and it made a big difference to surface finish & accuracy.

Bazyle17/01/2019 22:32:49
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4647 forum posts
185 photos

I would say it is perfectly normal to have a row of gib screws and for one to be say a cap head and be used for locking. Many gibs only have 3 screws. Since locking implies the movement provided by gibs is not in use there is no need for the screws not to be dual function.

It is no different from the description of lathes having both metric and imperial screwcutting capability. They are not independent - they use the same leadscrew and many of the gears in common.

SillyOldDuffer18/01/2019 10:21:10
4521 forum posts
971 photos

Are cross-vices worth having? Mine, admittedly not as well made as Bill's example, is useless!

I got one for my drill press and imagined it would work like a poor man's XY table. A sad disappointment - takes up a lot of room, fiddly to adjust, limited capacity, not very rigid, and no improvement in drilling accuracy compared with letting the drill float into a centre-pop in the normal way.

Now the vice lives under the bench waiting for the right job to turn up. So far nothing has. This tool is my worst buy ever, a complete waste of money. Since buying it I have been a broken man.

Cross-vices must be good for something. What am I missing?

Dave

Michael Gilligan18/01/2019 10:27:19
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13547 forum posts
586 photos
Posted by SillyOldDuffer on 18/01/2019 10:21:10:

Are cross-vices worth having?

Cross-vices must be good for something.

.

Mine [a hand-me-down from a well-meaning friend] was good for the Charity Shop

Having spent several years tripping over it ... I finally got round to donating it.

MichaelG.

.

https://www.model-engineer.co.uk/forums/postings.asp?th=117044

Edited By Michael Gilligan on 18/01/2019 10:38:01

Michael Gilligan18/01/2019 10:34:59
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13547 forum posts
586 photos

Bill,

If you decide to keep the slide, and add proper locking to it [separate from the gib strips]

this previous thread might give some design ideas: **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=121574

MichaelG.

[ personally, I would be inclined to return it ]

ega18/01/2019 11:41:22
1212 forum posts
101 photos

I bought one of these cross vices several years ago; on examination it was so badly made that I returned it next day.

The one in the picture looks relatively good and it should be a simple matter to install locks to the slides.

Fowlers Fury18/01/2019 12:20:16
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323 forum posts
72 photos

The link to the earlier thread provided by Michael G made for gratifying reading ~ thanks.
Always good to learn "you're not alone" !

After getting rid of the appalling cross vice (by name and nature) I purchased a hefty X-Y table at one of Warco's sale days. With an accurate vice on top, this has proven a much more usable bit of kit. There are two problems with the set up (1) the extra height of the X-Y table plus vice (2) the considerable weight which altho' the Startrite has a very substantial pillar & table, it was a big (age-related) effort to move the table up or down. This was solved by acquiring a small hydraulic jack.
The far-Eastern X-Y table required shims underneath to bring it exactly 90 deg to the quill but it does have locking screws for the slides, furthermore the (metric dont know } dials are reasonably accurate. If the OP has a big enough drill press & plastic card, an X-Y table might be the way to go.

Speedy Builder518/01/2019 12:40:55
1790 forum posts
127 photos

Bill P, How do you adjust the bottom slide as there only appears to be one adjusting screw - or is that what they call a "Slide lock". My Old Warco mill drill doesn't have a "slide lock" as such, you just over tighten one gib screw to lock it, so that method has been around for years on 'simple' machines.

Bill Phinn18/01/2019 13:53:08
185 forum posts
35 photos

Many thanks to everyone for the further suggestions, links and comments.

Bazyle, the only snag in the case of this vice is that not one of the six gib screws (3 for each axis) is a cap head; they are all standard gib screws with hollow hex heads and 10mm locknuts. The retailer though is claiming that all of the gib screws are for routine slideway locking, though clearly none of them, as they are, is actually designed for that. What's more, the item description leads the buyer to believe that on the one hand there are adjustable gibs and on the other there is some kind of independent slideway locking mechanism. This is clearly not the case.

Dave, the vice is actually surprisingly well made. Yes, there is a lot of backlash in the screws (one of the reasons a slideway lock is important on this vice - the handles turn a worrying amount of their own accord in response to vibration from drilling), but the build quality is in a different league from the cheaper cross vices I eyed up in a certain high-street machinery chainstore. They were truly wretched.

The main reason I wanted a cross vice is that I only have a bench drill and a tiny Proxxon MF70 mill, and I wanted the convenience of being able to drill sequential holes on larger stuff (i.e. with the bench drill) without having to reposition and re-secure the workpiece for every hole; (even if I wanted to, I can't hold work down with one hand whilst operating anything with the other because of injuries sustained in a road accident.)

Fowlers Fury, yes I did consider an x-y table and I may still go that route. My drill is certainly big enough. The only thing that tipped me towards this vice instead was that I would need a good vice to go on top of the x-y table anyway, and I don't own any machine vice except the tiny Proxxon one on the MF70, so I thought I might as well kill two birds with one stone and get this vice.

The retailer has still not replied. Ringing up just results in being told I need to speak to a technical adviser, all of whom seem perpetually to be otherwise engaged.

HOWARDT18/01/2019 14:49:30
426 forum posts
14 photos

Bill, as others have said the existing grub screws with locknuts are intended, or should be, to locate and set the gib to give the required sliding fit to allow axis movement. An additional central, to the length of the gib, screw without a locknut should be used for applying an additional locking force to prevent movement of the axis. The seller is trying to convince you that what they are selling is correct in having a locking feature that is doesn't have. Modify yourself or return if the selling blurb say's it has locking.

SillyOldDuffer18/01/2019 15:05:14
4521 forum posts
971 photos

Posted by Bill Phinn on 18/01/2019 13:53:08:

...

Dave, the vice is actually surprisingly well made. Yes, there is a lot of backlash in the screws (one of the reasons a slideway lock is important on this vice - the handles turn a worrying amount of their own accord in response to vibration from drilling), but the build quality is in a different league from the cheaper cross vices I eyed up in a certain high-street machinery chainstore. They were truly wretched.

...

Hi Bill. Can you report back after you've used your posh version in anger a few times please? I've not seen one that tidy before, and it's possible the one I bought is simply too cheap. Be good to know if a better made version overcomes the difficulties.

Ta,

Dave

Mick B118/01/2019 15:39:10
1124 forum posts
62 photos

Posted by SillyOldDuffer on 18/01/2019 10:21:10:

...

...This tool is my worst buy ever, a complete waste of money. Since buying it I have been a broken man.

Cross-vices must be good for something. What am I missing?

Dave

Hmmm. I detect a faint trace of hyperbole... laugh

I nearly bought one when I was about 17, but someone told me then that they weren't very good. I didn't at first think they knew what they were talking about, but I kept on asking everybody if anybody knew anybody else who'd ever used any one of these successfully to do anything, and nobody replied.

I think I must've lost interest, or found another way to do whatever it was in my tiny mind at the time - 'twas a long time back.

Proper slide locking screws may be interspersed in the row between gib adjustment screws, but are longer and don't carry a locknut. Gib adj. screws might be grubscrews, but locking screws usually have a cap or head. I'd think it's probably a Trades Descriptions offence to describe an adjuster as a lockscrew, for the very good reason the OP gives about messing up a carefully-worked adjustment.

The slides in the crossvice in the photo still look rather short for milling, and I can't see that the moving vice-jaw has much parallel guidance - so I can't really visualise how vice-like its grip really is.

Neil Wyatt18/01/2019 15:58:21
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16248 forum posts
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Ironically this does look better made than the usual with more robust castings.

I suspect that it was supposed to be fitted with a thumbscrew in the central hole of each gib like the ultra-cheap versions. You don't need three on such a short gib for a non-precision use like a cross vice on a drill. It's possible that the earlier batches were and they've been caught out by not noticing the change and altering the product description.

Perhaps ask the seller if they can send a pair of suitable screws as a replacement.

At least they aren't be advertised as 'suitable for converting a drill press for light milling' which one company used to say in the deep past!

Neil

Clive Foster18/01/2019 22:14:11
1776 forum posts
57 photos

Looks like I'm on my own as being respectably satisfied with my cross vice. As mentioned earlier mine is an older 6" version which appears to be bit more substantial than the later types and has a rod type guide for the moving jaw.

Yes the screws are sloppy and the gibs not wonderfully precise but it is what it is. An effective device for moving parts around to bring them into alignment with the drill before making a hole in the right (we hope) place. With the thumb screw locks tightened up it holds quite securely enough for any sane job.

OK its not a proper X-Y table with precision, graduated screws. But at the price I paid, £60 - £70 from memory many years ago, any such expectations would have been totally unreasonable. I was a little disappointed by the general fit and slop but it worked. One thing I did have to do was swop the hopeless plain, smooth, flat vice jaws for a pair of prismatic type. NuTool brand so no longer around but no doubt similar can still be found. One horizontal Vee groove and three vertical ones of different sizes. Turned a dubious in the extreme device into something eminently useable within its limitations.

Proper co-ordinate drilling gets done on the Bridgeport which has a 3 axis glass scale DRO set fitted.

Here is a job we did this afternoon.

cross vice tapping.jpg

Hollow stainless steel oil union around 25 mm long with 27 mm AF hex and M23 x 1.5 external threads held in a 5C collet about to receive an M16 x 1.5 through tap. Pollard No 4 tapping head driven by Fredr'k Pollard 15 AY drill put the tap through "just like that". Two done in a couple or three minutes. Cross vice locked up by thumb screws in both axes didn't even blink.

The vice pretty much never comes off the big 15 AY drill. Maybe one or twice a year. Normal configuration is with a flat "improved wood" table held on via a wide batten underneath.

cross vice normal.jpg

Ideal for sheet or many smaller components that can be held down by a few strategically placed twin thread screws zapped in with a battery drill. Or clamp to the overhanging sides with G, tool or friction type trigger clamp. Have a smaller one too for similar work. Easily removed when I want to use the naked vice.

The plate shown is probably past its best but I have a stack of old kitchen furnishing panels up in the shop attic to make a new one from.

Clive.

Edited By Clive Foster on 18/01/2019 22:15:06

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