Thread: Bench grinder tapered spindle off centre

No there is no trick they should be right , you could re machine however it would not be cost effective or practical, maybe contact Josco and see if they will replace itI have always used this brand and have no problems Taper Spindles For Bench Grinders - 140mm Overall - Products - Precision Specialty Tooling

I have a 16 mm Josco tapered spindle and it is fine.

RE: "They both fit on the grinder"
That is not right - only one should fit fully onto the grinder.
If the grinder spindle thread is 16 mm and a 5/8 has been jammed onto it then this may have damaged the thread.
The same for the 16mm on a 5/8.

If they both fully fit then the thread on the grinder spindle has been cut undersize which would explain the problem.
I would check this out before buying more spindles

Thanks for that. I've done some more measurements, and the two spindles I have are off-centre in different directions, so it's definitely the spindles. I'll be taking them back and try to get some decent ones elsewhere.

Originally Posted by BobL

If they both fully fit then the thread on the grinder spindle has been cut undersize which would explain the problem.
I would check this out before buying more spindles

Hmm, interesting. How can I check this out? The thread doesn't look damaged at all. I've measured the OD of the thread, and it's 15.2mm (15.3mm on the other end). It is quoted as a 5/8" thread (Jet is an american brand), and 16mm is larger than 5/8". Both spindles are quite wobbly until the last moment of tightening where is seats into position, but that is similar to my other grinder in that respect. I also tried thread-taping around the thread and on the shaft as well, so that everything was tight, but it made no difference.

Originally Posted by surfdabbler

Hmm, interesting. How can I check this out? The thread doesn't look damaged at all. I've measured the OD of the thread, and it's 15.2mm (15.3mm on the other end). It is quoted as a 5/8" thread (Jet is an american brand), and 16mm is larger than 5/8". Both spindles are quite wobbly until the last moment of tightening where is seats into position, but that is similar to my other grinder in that respect. I also tried thread-taping around the thread and on the shaft as well, so that everything was tight, but it made no difference.

Those threads sound worn to me.

A well made 16 mm thread will be about 15.85 mm OD, a 5/8" (15.875mm) will be ~15.7mm OD.
15.2 / 15.3 mm indicates a well worn thread and are likely to be the cause of the problem.

What are the Jet spindles?

The jet spindle is quoted as 5/8, and is 11TPI, so matches UNC thread. The thread does have a flat top, and looks to have been machined that way, so this might explain the slightly small OD measurement. Hare and Forbes carry the Precision Tooling spindles, so I will bring my grinder in and check the fit before I buy them.

Thanks for your help!

Solved! I got one of the precision tooling spindles from Hare and Forbes, and it's great. Put it on, and it went straight on, perfectly centred. Thanks for the recommendation.