Lathe Bearings

[glr1109]

I just puchased a Marshall Lathe. I would like to replace the bearings on the headstock.

What infomation would I need to give someone, in order to purchase a set?

Where would I find them?

Greg

[glr1109]

I just puchased a Marshall Lathe. I would like to replace the bearings on the headstock.

What infomation would I need to give someone, in order to purchase a set?

Where would I find them?

Greg

[Julian Smith]

If the bearings are sleeve type they will probably have to be made at a GOOD MACHINE SHOP.
If they are a standard ball bearing with a number on the side,take the bearing to most any automotive parts supplier and check the number for availibility.
J Smith

[glr1109]

I found a "set" at MSC. What I ordered were: Double Sheilded/Radial Ball Bearings. Does anyone know if this was the type used originally? They look like the type that I took out of it. I'll know in a day or two if they will work(unless one of you know).

Thanks
greg

[Gnomon]

Ball bearings come in a wide variety of grades. The bearings in a WW lathe, would usually be of the finest grade, both for runout, and for rumble. A common jobber grade bearing, such as you will get from MSC, or Granger will be much poorer than the original. This will manifest itself as a poor looking finish on turnings.

As an aside, the best ball bearing headstock has between 10 and 100 times more rumble and runout than does an average cone bearing headstock.

-Chuck Harris

[glr1109]

If it is not obvious...I don't know anything about which bearings are better than the next. Do you have any brand names? Retailers? Also, what type? It's been suggested that I get a bearing that has two rows as opposed to one. Tapered Bearings are better than cylinder etc.


The size that I need are:
#1..ID=12.72mm, OD= 28.52mm, width is 8mm
#2..ID=12mm, OD=28mm, width is 8mm


I appreciate the help!

Greg

[Gnomon]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by glr1109:
If it is not obvious...I don't know anything about which bearings are better than the next. Do you have any brand names? Retailers? Also, what type? It's been suggested that I get a bearing that has two rows as opposed to one. Tapered Bearings are better than cylinder etc.


The size that I need are:
#1..ID=12.72mm, OD= 28.52mm, width is 8mm
#2..ID=12mm, OD=28mm, width is 8mm


I appreciate the help!

Greg <HR></BLOCKQUOTE>

Oh Boy! That is a tall order. Just a description of the various styles of ball bearings takes two pages of a "Machinery's Handbook".

If your lathe has only two ball bearing units, one at the front, and one at the back of the headstock, they will need to be a type that can handle both radial and thrust loading. These are called "angular contact" bearings, and are available in either a single row, or a double row. The single row type can only take thrust in one direction, the double row type can take thrust in both directions. If it has a separate thrust bearing (looks like a flat washer with balls), you can use radial contact bearings.

The problem here, is there are 4 types of single row, radial contact, and 8 types of single row, angular contact. Each is good for a specific class of loading. For your purposes, whichever style is available would suffice.

Then, we have to figure out the quality of the bearing. That is the ABEC numbers that you may have heard skateboarders bandy about. ABEC-1, 5, 7, and 9 are for ball bearings, with ABEC-1 being the jobber grade, and ABEC-9 being the absolute best grade.

The radial runouts are as follows: ABEC-1 = 0.0004", ABEC-5 = 0.00015", ABEC-7 = 0.0001", ABEC-9 = 0.00005". Your lathe would probably have used ABEC-9, but possibly a selected ABEC-7 was used. Sherline uses ABEC-5. Derbyshire uses ABEC-9 in their 8mm lathes. Add 2-3 more zeros to the ABEC-9 spec, and you have the typical 8mm cone bearing spec.

ABEC-7 and 9 bearings are very expensive! I would first take a stab at cleaning the original bearings. Usually, they are just gummed up. If they won't clean up, usually, the bearing information is on the dust seal, or etched on the edge of the outer race.

-Chuck Harris

[glr1109]

Thank you...This will give me some idea of what I need. The bearings that are in it now are(I think) fairly cheap bearings. The name on them is "NORMA", followed by the numbers: 6101PP(left) and S5RPP(right).
The problem is that the bearing unit in the headstock on the left(as you look at it)looks as if it were banged in. As long as I'm going to replace one, I would like to replace the other. So I might as well do it right. I'll let you know how I make out.

Do you have a name of a company/retail to start looking?

Thanks Again
Greg

[Gnomon]

Hi Greg,

Unfortunately, I don't have much need for bearings that are any better than the usual ABEC-1 jobber grade that is available everywhere. MSC has a very broad selection, and they will probably order specials for you. Beware, these bearings cost nearly $100 each. One other place that ABEC-7 and ABEC-9 bearings sometimes appear is in hard disc drives for computers. They are used for the spindle bearings for the disk platters. Old 5 inch full height hard drives have excellent bearings which are about the size you need. When you remove a ball bearing you must never apply pressure to the balls... in other words, don't force the bearing off of the shaft using the outer race.

For what it's worth, the measurements you have given appear to be standard sizes. The 12x28x8 is a standard 6001ZZ which is a metric bearing, the 12.72 x 28.5 x 8 is probably actually a: 1/2 x 1-1/8 x 1/4 which is an R8.

I would try to save the original bearings.

-Chuck Harris