Myford ML4 gib strips

Where can I get new gib strips for my Myford ML 4.

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I suspect you will need to make them ... which might only mean ‘make from’ another item.

Do you have the old/worn/bent ones as a pattern ?

MichaelG.

Sorry for hijacking your question, but it is on subject.

I'm nearly finished restoring a mini 1940's milling machine, it doesn't have tapered gibs, I need to make a small gib strip, would a strip of en1a be suitable to make a gib strip from? I thought the lead in it might give it some lubricity?

Pete

Personally ... I would use gauge plate, for its flatness, smoothness, etc.

Lubricant can be applied

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I’m sure there will be other opinions forthcoming.

MichaelG.

Interesting. No idea though. Why were they not originally made from phosphor bronze.

Steve.

Edited By Steviegtr on 07/05/2020 00:45:03

I suppose gauge plate is harder so it might be better for vibration (not absorbing it and effecting surface finish?).

I did measure some bright en1a flat bar with a mic, and it was surprisingly consistent along the length and close to spec, which made me wonder if it could be used as gib strip.

It would be interesting to hear others opinions on it though.

My take on this, is that a gib strip runs on usually cast iron. we all know from metallurgy that for 2 metal rubbing together that one would be made from a hard metal substance & one from a soft substance. Hence my reasoning of cast iron to Phosphor bronze. Especially as the bronze can be oilite. It will stay lubricated for longer than any other metal. Or is it too soft & would not pack correctly. Silly old duffer will have an answer in the morning I am sure that will blow my theory away.

Steve.

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Good morning, Steve

Just wondering ... have you looked at the strips on your Myford ?

MichaelG.

High Michael,

I do have the original gib strips in the lathe and would like to replace them with new items as I have a problem with inconsistent fit, resulting in tight spots.

I was hoping that the sizes could be the same as say a ML 7?

Myford quote online 8 1/2 inches long for the cross slide, but of course it doesn't say what the other dimensions are.

Steven

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I’m sure that collectively, the forum can compare the dimensions of various strips with what you have ... but that would be easier if we know what you need.

If it’s any help: Here’s a couple of photos of my ML7R strip, in the condition I bought the lathe

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I think you will find it differs significantly from the ML4 version.

Incidentally: I managed to straighten that and polish it back to useable condition

MichaelG.

Edited By Michael Gilligan on 07/05/2020 09:11:38

I think Michaels suggestion of gauge plate is a sound one. the strips are hard ground metal surface and gauge plate would fit the bill nicely. There will also be longer lasting than bronze ones which may flex with the limited adjusting screws on the ML4.

Alternatively you could rub the original on some increasingly fine wet and dry with oil, on some plate glass or a granite chopping board. then once done check for flatness using a verdict DTI on the surface plate (granite chopping board). If you want to completely replace it then I think that gauge plate is your first option, not sure of the dimensions on the ML7 and how they compare to the ML4. but if they are the same, a new ML7 one cut down to size would be a more expensive option.

When I made some gib strips a few years ago I used gauge plate and did as Jon suggested to flatten one surface. Incidentally the thickness of the strip does not need to be perfect since the back face is only in contact with the gib screws.

One other thing I did was to cut the ends with a sharp endmill (a new carbide one in my case ) so that the end edges in contact with the slide had no discernible rounding. This helps to prevent any fine chips getting trapped between the gib and the slide.

Doug

Tight spots is usually down to wear on the cast iron ways on the cross slide or carriage. The more used area gets worn away over the years. Are you sure your problem is the gib strip?

You should be able to rub your gib strips on emery paper on a slab of glass of granite etc to flatten them out as already suggested. They they are adjustable via the screws so flatness is not ultracriticical as they will conform to the pressure of the screws etc.

To make new gibs you will need to machine the angles on the edges etc. Mild steel or gauge plate will work. It is rubbing against cast iron, so a good bearing combination. No need for bronze etc.

Theory safe, but I can fill in some of the whys and wherefores! Not due to my natural genius, but I do have a collection of books!

• D.A.Low's "Applied Mechanics" (Longmans, London 1947) has much of interest to say about Mr Beauchamp Tower's researches. Stephenson, Brunel and Whitworth are remembered despite their efforts being mostly obsolete. Poor old Tower is mostly forgotten, but he's the guy who sorted out modern lubrication, a far from simple subject. Unfortunately Low doesn't explain why two different metals should be used in a bearing.
• "Engineering Hand-drawing and Scale-Drawing" Jackson & Bentley, Leeds undated is full of drawing exercises covering common pre-war engineering objects, together with a short description of design features. For a cast bearing, it says 'BB is a Brass "Bush" or "Lining". The use of this liner or bush tends to reduce the "wear" of the "journal" by making it "run" more easily and smoothly than if it were rubbing on the cast-iron. (The bearing can also be renewed cheaply and easily by putting in a new bush)"
• "Introduction to Machine Design, Jefferson & Brooking, Ronald Press, New York 1951" gets into the nitty gritty:
  • Sufficiently strong to bear the load
  • Readily machinable and able to take a high degree of polish
  • Have low frictional resistance
  • Able to function within the temperature range of the machine
  • do not readily gall, ie seize

Of these, not galling, generally means a bearing must be made of two different metals. The book says the main exceptions are: cast-iron may be run against cast-iron, and mild-steel may be run against hardened steel. Not any pair of different metals work without galling, examples of OK pairs given are:

• Babbitt metal, good for heavy pressure and shock loads because it's plastic. Failed bearings don't score.
• Brass, takes more pressure than Babbitt, but not good for shock loads. Cheaper than better bearing metals, main advantage - easily replaced
• Bronze, very high pressure
• Copper-Lead, good for high-pressure and high-temperature in engines. Failed bearings don't score.
• Silver, and Silver Cadmium, high load, high speed, precision machines
• Powdered metals (Oilite etc), low load, low speed, low maintenance (ie machine is done when they wear out)
• Plastics, water lubricated, high-pressure, dredging machines
• Rubber, water lubricated underwater bearings
• Cast-iron with hardened steel, slow speed light load machines, cheap
• Steel, sliding bearings, especially ball and roller bearings. (polished to better than 0.0001" with high hardeness and toughness.)

So Phosphor Bronze is OTT for lathe gibs, cast-iron more likely, maybe mild-steel for cheapness, or brass because it can be polished. Big machine slides might be different, but gibs don't generally have to cope with high-pressure, high-loads, or high-speed. Be fun to fit silver gibs, massive boasting rights, and it would deter vampires!

Dave

Dave

Yes Michael, they look like mild steel.

Steve.

Great write up you did there.

Steve.

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Dave has already done his duty well ... but I will just add that [suitable grade] cast iron is sufficiently ‘self lubricating’ to run well; either cast on cast, or steel on cast.

Machine tool makers have been doing it for many decades.

MichaelG.

Ok keep your hair on. Too early to argue. Was only a thought.

Steve.

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... I made a simple statement, in response to what I took to be your question

No hair or argument involved.

MichaelG.

Steve.