Replacement For Logan Headstock Double Row Bearing

James_Douglas said:
After weeks of research and a dozen conversations with bearing manufacturers I came up to a brick wall on finding a "correct" bearing for the Logan Lathes. There are several bearings that will in fact fit dimension wise, however the key design parameter is the fact that the original bearings had a preload in them.

The manufacturers all make a single row bearing with a preload, but no double row bearings.

I called Logan lathe and talked with Scott Logan before ordering his bearing. Since Logan Actuator sells the bearings, at a much higher costs than the other dimensionally same bearings, I wanted to know which of the 3 or 4 preloads that are generally available by the manufacturers he was using. I was interested in going up on step if possible. Since the bearing is a special order non-refundable item I wanted to know if there was any choice.

Scott would not discuss in detail the bearing. All he would say was that the bearing met the original specifications.

Below is an email I sent to Logan Actuator yesterday in the morning. I am waiting on an answer.

--------------------------------------Original Message---------------------------------------------------

From: James Douglas

Sent: Monday, April 13, 2015 10:35

To: 'Logan Actuator Co.'

Subject: Question on Logan 820 bearing

ATTN: Scott Logan,

Hello Scott,

I don't want to beat a dead horse. However, I was suspired when I opened the box with the bearings inside. They are SKF. Prior to talking with you on the telephone and prior to ordering the bearing from you, I had talked with SKF and a lot of other bearing manufacturers. They all told me the same thing. They did not make any double row bearings with a built in preload.

I assumed that you were having the bearings made by a specialty house with a preload just as the original 5000 series New Departure bearings that Logan used in the 820 lathe (see attached).

I emailed and talked with SKF engineering this morning. I read them off the part number on the box and the part number off the bearing. Their response was:

****************************************************

SKF 3208 A-2Z is by design a bearing that has internal clearance. This bearing has axial internal clearance equal to 0.0004/0.0011 in. which is considered in the "normal clearance" range. Other identifiers in the part number to specify internal clearance are:

C2: axial internal clearance smaller than normal

C3: axial internal clearance greater than normal

C4: axial internal clearance greater than C3

Again, this bearing cannot be preloaded as manufactured.

*****************************************************

There is no marking on the box or the bearing to indicate that it is anything other than a what SKF calls a "normal clearance range". Also, they stressed that clearance range and preload are not the same things and I was told not to confuse the two. They also made it clear that this bearing "cannot be preloaded as manufactured".

Since the preload is what makes the lathe shaft not walk forward or back and there is no provision to set any preload on the shaft (by design) then the bearing needs to have a preload.

Can you shed any light on this for me please? If the bearing was drop shipped, is it possible that I did not get the correct bearing?

Thank you for your time.

James.
------------------------------------------------------------------------------------------------------------------

If anyone can shed any light on the bearing issues I would be grateful.

It appears that what I got from Logan was a "tighter" bearing than the other generally available bearings of the same size, but still without a preload of any kind. If you see the attachment, which is a page from a New Departure catalog 19th edition 1948, all 5000 series bearings had a preload. The Logan 45508 bearing is a 5000 series ND bearing. The 4 in the number just denotes a snap ring.

I am starting to get somewhat upset with the fact that I did my homework, talked (or tried) with Scott Logan about the bearing and its issues, spent the money for his part numbers and then got a bearing that the manufacturer tells me has no preload which by definition does not equate the original specifications.

When I get a response I will let people know. And again, if anyone has any insights, I am all ears.

James

View attachment 99588 View attachment 99589
Click to expand...
 
I realize that this is a very old thread, but I am curious to know the outcome of your bearing problem. I have a Logan Powermatic 11" lathe, apparently one of the last made (from odd parts it seems) before the company ceased operation. Model number 1110008H, l which I have yet to find a manual for. I have terrible noises coming from the headstock which I am assuming are from bearings, as the noise persists when turning the headstock by hand without the Reeves drive engaged. I have been reluctant to try to tear into the headstock because of the confusion about the availability of replacement bearings. Did you ever get a satisfactory bearing to substitute for the originals? I'm not sure whether he even has the bearings, although I see one pair listed on the Logan site as being over a thousand dollars.

Thanks Thomas Moseley
James_Douglas said:
After weeks of research and a dozen conversations with bearing manufacturers I came up to a brick wall on finding a "correct" bearing for the Logan Lathes. There are several bearings that will in fact fit dimension wise, however the key design parameter is the fact that the original bearings had a preload in them.

The manufacturers all make a single row bearing with a preload, but no double row bearings.

I called Logan lathe and talked with Scott Logan before ordering his bearing. Since Logan Actuator sells the bearings, at a much higher costs than the other dimensionally same bearings, I wanted to know which of the 3 or 4 preloads that are generally available by the manufacturers he was using. I was interested in going up on step if possible. Since the bearing is a special order non-refundable item I wanted to know if there was any choice.

Scott would not discuss in detail the bearing. All he would say was that the bearing met the original specifications.

Below is an email I sent to Logan Actuator yesterday in the morning. I am waiting on an answer.

--------------------------------------Original Message---------------------------------------------------

From: James Douglas

Sent: Monday, April 13, 2015 10:35

To: 'Logan Actuator Co.'

Subject: Question on Logan 820 bearing

ATTN: Scott Logan,

Hello Scott,

I don't want to beat a dead horse. However, I was suspired when I opened the box with the bearings inside. They are SKF. Prior to talking with you on the telephone and prior to ordering the bearing from you, I had talked with SKF and a lot of other bearing manufacturers. They all told me the same thing. They did not make any double row bearings with a built in preload.

I assumed that you were having the bearings made by a specialty house with a preload just as the original 5000 series New Departure bearings that Logan used in the 820 lathe (see attached).

I emailed and talked with SKF engineering this morning. I read them off the part number on the box and the part number off the bearing. Their response was:

****************************************************

SKF 3208 A-2Z is by design a bearing that has internal clearance. This bearing has axial internal clearance equal to 0.0004/0.0011 in. which is considered in the "normal clearance" range. Other identifiers in the part number to specify internal clearance are:

C2: axial internal clearance smaller than normal

C3: axial internal clearance greater than normal

C4: axial internal clearance greater than C3

Again, this bearing cannot be preloaded as manufactured.

*****************************************************

There is no marking on the box or the bearing to indicate that it is anything other than a what SKF calls a "normal clearance range". Also, they stressed that clearance range and preload are not the same things and I was told not to confuse the two. They also made it clear that this bearing "cannot be preloaded as manufactured".

Since the preload is what makes the lathe shaft not walk forward or back and there is no provision to set any preload on the shaft (by design) then the bearing needs to have a preload.

Can you shed any light on this for me please? If the bearing was drop shipped, is it possible that I did not get the correct bearing?

Thank you for your time.

James.
------------------------------------------------------------------------------------------------------------------

If anyone can shed any light on the bearing issues I would be grateful.

It appears that what I got from Logan was a "tighter" bearing than the other generally available bearings of the same size, but still without a preload of any kind. If you see the attachment, which is a page from a New Departure catalog 19th edition 1948, all 5000 series bearings had a preload. The Logan 45508 bearing is a 5000 series ND bearing. The 4 in the number just denotes a snap ring.

I am starting to get somewhat upset with the fact that I did my homework, talked (or tried) with Scott Logan about the bearing and its issues, spent the money for his part numbers and then got a bearing that the manufacturer tells me has no preload which by definition does not equate the original specifications.

When I get a response I will let people know. And again, if anyone has any insights, I am all ears.

James

View attachment 99588 View attachment 99589
Click to expand...
 
My experience is with the Logan 400 lathe, but you write the following: "Since the preload is what makes the lathe shaft not walk forward or back and there is no provision to set any preload on the shaft (by design) then the bearing needs to have a preload" I believe the answer to your concern is the design of the Logan spindle and the purpose of the 'Bellville Washers, LA-1016." The Bellville washers provide considerable tension along the axis of the spindle to keep the spindle from moving and provide loading for the spindle bearings. BTW, the Logan 400 has one pair of Bellville washers and the 820 has two pairs of Bellville washers.
 
My lathe is an Atlas 3996 bought new 40+ years ago. As some of you may know and most of you probably won't care, the 3996 has Timken tapered roller spindle bearings rather than one double-row and one single-row ball bearing that AFAIK all Logan lathes have for spindle bearings. So I have no personal reason to care whether the stock SKF or ND bearings are made with or without a built-in preload so that the spindle in the head stock has no end-float. However, I am a graduate engineer and it appears patently obvious to me how with two rows of bearings this might be achieved, at least in theory. So it seems quite misleading to me for any SKF or ND engineer to claim that there was no way designed into the double-row bearings to achieve this. Which an earlier poster in this long-running thread said that at least one engineer had claimed. I am not sure why he might have said it as it would have no effect on the number of bearings that they were going to sell.
 
wa5cab :
"it appears patently obvious to me how with two rows of bearings this might be achieved, at least in theory."

And what would that way be? the aforementioned Belleville washers or something else?
 
First, let me repeat that I personally have never seen one of the original Logan bearings but my understanding is that the original bearing nearest to the chuck had two rows of balls and two ID and OD grooves and the bearing at the rear end if the spindle had one. And that the installation procedure somehow guaranteed that the two bearings were properly installed. Also, I don't recall anyone ever mentioning any Bellelville washers. until recently.

But anyway, the theoretical way to make a preloaded 2-row ball bearing would be to grind one of the ID and OD groove pairs exactly the same distance from some reference plane. The other pair of grooves would be ground with one of the 2 grooves slightly offset from the theoretical location. And one could further complicate the procedure by grinding both of the ID or both of the OD grooves slightly offset in opposite directions and have a bearing that was pre-loaded in both directions. However, as the bearing temperature rose, the preload would increase. Unless anyone knows of a suitable bearing or ball or material with a negative temperature coefficient. Anyway, it probably would be cost-prohibitive.
 
Here is my 2 cents worth. I finished rebuilding my Clausing 8530 mill recently. Did a bunch of bearing research whis is now paying off as I'm rebuilding my Logan 1935-2.
I really doubt that the front bearing was a double ball bearing. It's narrow width at 16mm would make that really expensive. That's why I couldn't find one that fit the demensions. But the front opening is big enough width wise to take a larger width double ball bearing. I'm going to see about that tomorrow. What does Scott sell for a front bearing? Is is 16mm wide or larger?
The widest bearing that could fit is just shy of 25mm but probably 22-24 mm would be it. Not enough room to stack 2 16mm bearings. Won't fit.
 
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I just got off the phone with Scott. Rear bearing 120, front bearing 133. None angular. Not double row. I read him my kdd bearing numbers and he checked that they were the correct sizes. So, Logan just used plain ball bearings but probably a high quality one.
 
I had to call Logan again for parts, so I also asked if they ever had an 11 inch lathe with 2 set's of front bearings. He pondered for a minute and said yes. But not a double row, just 2 bearings.
 
The spindle, bearings, and design for the 10" & 11" are not the same. Scott has the bearings for the 10" made. There are several threads on the topic. Last year on the groups.io forum he moderates, he was the most forthcoming I've seen in my ~ 10 years of Logan ownership on why the 10" spindle bearings are unique. Some believe it's 100% hype and purchase other bearings. IMHO Scott up front told you what's needed for the 11" because they are not the same specification as the 10" nor is it set up the same way and he has no reson to tell you anything different. The parts drawings show different bearings. The 11" uses two Bellevue washers for the preset. My understanding is the 10" has the spindle fixed in the unique front bearings and the spindle is basically allowed to expand through the rear bearing. There is a take-up nut, no Bellevue washers. Neither the 10" or 11" manual has special reassembly instructions. There are internet postings/discussions on adjusting the preset and IIRC Scott has discussed it.

A very interesting book on the demise of the machine tool industry, "When the machine stopped." tells some of the Logan story. There is an archived Washington Post article that fills in some other details. Logan had long before sold the company to the Houdaille conglomeration when the last "Powermatic Logan" was produced. A British company bought Houdaille in a fire sale for one company, John Crane Packings, and closed everything else. My suspicion is Scott's family bought up everything "Logan" they could from the Kentucky Powermatic factory disposal and took it back to Chicago. And had the foresight to grab Lathe.com. For what it's worth.
 
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