Thread: Hercus AR Headstock Bearings

your attachment sad but true in this day and age.This Hand Forbes firm has good working principles none the less and have been of wonderfull service to me personally over the years.

Peter

Hi Ken
Finally found the paperwork on the berings! I actually received the bearings in July 2003 - so much for my memory chip.


The prices ex GST were 18685 $321.77; 18620 $273.55; 14138a $369.75 and 14276 $210.38.


You may also consider using another brand of bearing, such as NSK, and Naichi, and shop around for best price; could save yourself some money. I have just done 4 sets of magneto bearings for my toolpost grinder spindles and saved a bit by shopping around - not a fortune but certainly worth the effort

Also the internet is a great source of info on bearings - the existence of sizing standards mean that other makers will be able to provide the same size bearing. Not sure about precision classes though.

Good luck

John

Hi Me again
Just a few points I would like to add in closing.

1. if you use precision class bearing be sure to check for the runout marks on the outer (cup) an align these when installing - I think the inners (cones) have the same.

2. Also be sure to apply the correct preload and adopt a appropriate run-in procedure - this usually mean staking te spindle through teh various speeds from low to high for 10 or 15 minutes each. Check frequently for temperature and if the bearings are getting too warm stop and allow to cool before proceeding to complet the procedure.
Cheers
John

Hi John,

Thanks for your info re bearings.

Q1. Just to set me absolutely straight, were the above prices for precision 3, or standard precision?

Q2. Does precision 3 apply to the inner race, outer race, or both?

I have looked at my front bearing outer cone, and cannot see any additional markings to indicate that it is precision 3.

All that is written on the end face is,
TIMKEN 18620 MADE IN USA, and the letter E.

If someone can through some extra light on this subject, I would appreciate it.

I have been unable to extract the rear bearing outer cone, so am forced to reuse it.

The rear bearing, in any case, looks to be perfect, it's only the front bearing inner cage and rollers, that's rusted.

Ken

Hi Ken
Yes those prices were for precison class 3 bearings. And yes the class applies to both the cup and cone.

Not sure about your lathe but I have seen on Hercus lathes two small holes in the casting directly behind the machined area for teh bearing cones - these allow a pin punch or similar to be inserted so the cones can be driven out.

The front bearing cup I replaced was Timken made in England marked S which indicates a precision class bearing but the rear one like yours had no class markings. However, given the age of the machine it is hard to know if Timken just supplied Hercus with a job lot of precision bearings for its lathes, mills etc and/or the bearings had been replaced with non-precision bearings at some stage in the life of the machine (which is probably older than me).

The E suffix may have been used to indicate a high load design or it may have had no significance at all.

I can only restate my view that using standard bearings will almost certainly mean that the rebuild will not meet the standards of accuracy which the lathe was originally built to. The extra cost reflects the time and expertise needed the make a bearing that exceeds those standards. The spindle is the heart of your lathe - the performance of the machine in terms of accuracy begins and ends right there.

Good luck

Cheers
John

Just an idea Ken .......... mabey you could freeze the old bearing shell with gas.
It would only take 30 seconds or so to freeze a bearing of that size, although
those little holes that John mentions, are worth a six pack IMO.

I sent an email to Timken, and received the following information from them.

Class 3 bearings are intentionally made that way, not just the result of grading.

Class 3 applies to both cup and cone.

There is an engraved dot on the outer cone to indicate a precision bearing, and this dot coincides with the high point of concentricity.

The letter E designates the year of manufacture.

I also received two interesting data sheets with reference to precision bearings.


Ken

I wonder what class of bearings are in machines churned out in Asia these days???

Originally Posted by Sheraton

Also the set of bearings for the Hercus lathe is the same as that fitted to the Hercus Model O and OM milling machines (I know cause I have one - the milling machine not the lathe).

This info is incorrect. The Mill bearings are not the same. How do I know? Well I bought the Lathe Bearings because I had bought a Mill on Ebay and thought I'd get in early and order the bearings before the Mill got here. I also bought the Manual for the Mill and then found out what the correct bearings are.

Nev