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J & S surface grinder - refurbishment

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gerry madden08/11/2021 12:29:34
252 forum posts
132 photos

Chaps, my 540 should have a little locking thumb-screw on the dial for the height adjustment but it seems to have gone walk-about sometime in a previous life.

I could of course re-invent the wheel with my own design, but if anyone can send me a picture of the real thing please, or even just a length/dia/knurl-pattern/brass/steel description please if that's easier I would sleep easier at night (I'm ok on the thread size.) Thanks in advance.


Dave S08/11/2021 17:40:58
370 forum posts
90 photos

Mine has a SHCS in it. Was like that when I got it…


Chris Crew09/11/2021 23:44:33
208 forum posts

I can send you a picture but not sure how to do it here. if you PM me with an email address I will forward it to you, but I would suggest its really not necessary because it's just a screw with a flat head about 0.5" dia. straight knurled on the edge if the one on my machine is original. If you know the thread you could make something to fit in about 5 minutes max.

gerry madden10/11/2021 03:30:42
252 forum posts
132 photos

Hi Chris,,pm sent. Yes it should be a simple job to do.

Re the thread, I did think I knew what it was, but that 'thought' somewhat fell apart when I checked more thoroughly. I expected it was a 1/8BSF but this is far too floppy. Currently the best fit screw from my tray of miscellaneous is an M3.5 which makes no sense at all ! All good fun!


DiogenesII10/11/2021 06:43:55
563 forum posts
221 photos


noel shelley10/11/2021 11:00:09
1353 forum posts
21 photos

I go along with 4BA ! A lot of BA was used in the 60s. Noel.

Mark Rand14/11/2021 12:26:34
1275 forum posts
28 photos

Sorry for the late reply.

I've just been using my 1976 vintage J&S 1400 grinder and took the opportunity to take the height dial locking screw off and measure it.

Mine is 1/8" (actually 1.205" od) X 40 tpi. The thread are 3/8" long. The head would have been 5/16" dia before knurling X 1/8" thick. This might not apply to the 540, but it's a possibility.

Howard Lewis14/11/2021 16:44:57
6120 forum posts
14 photos

0.125 x 40 tpi might be 5 - 40 ANC. The 60 degree thread angle would distinguish it from the 0.125 x 40 tpi 55 degree 1/8 BSW thread form that we would also call 1/8 Model Engineer.

Nearest BA to 0.125 would be 5BA at 0.127" x approx 43.1 tpi

4 BA is 0.1417" 3.6 mm ) OD x approx 38.5 tpi


Mark Rand14/11/2021 17:10:04
1275 forum posts
28 photos

It won't be ANC. All the other threads are BSW or BSF. It's 1/8" Whitworth.smiley

I've got metric, US, Whitworth and BA thread gauges and the only one that fit was 40tpi. I did originally wonder if it was 5BA, but the pitch is way off for that.

Note that BSF isn't specified below 3/16" but BSW is specified down to 1/8" in  BS84-1956. Amusingly, Meccano threads of 5/32" 32tpi aren't an 'official' standard either.

Edited By Mark Rand on 14/11/2021 17:34:29

gerry madden17/11/2021 00:13:26
252 forum posts
132 photos

Thanks all for your additional thoughts.

I really thought I had cracked all this thread identification business, especially as I now have the benefit of my OMT complete with its oculars for thread angles. But this one gave me real trouble. After a lot of humming and haa'ing and endless perusing of tables I decided it had to be a 5BA and bought at tap and a die. When I got them I put the tap in the hole and like every other tap I tried it was a wobbly fit. Well perhaps the hole was just on the top of its tolerance range, I thought....., I therefore turned up a screw using the new die opened out to its absolute maximum hoping this would sort it. Sadly it didn't as even this was also a rubbish fit.

Time for drastic action. Whether it liked it or not this hole was going to become a 4BA. Somewhat surprisingly the 4BA tap didn't create a mangled mess and in fact made a nice job. I made up a screw to Chris C's dimensions but with a 4Ba shank and it fitted beautifully.

I'm sure some people think I'm nuts but when finally something goes just as you want it to isn't it a nice feeling ?!


gerry madden06/12/2021 12:02:24
252 forum posts
132 photos

As I expected I'm being sucked into fast to doing a complete nut and bolt refurb of my 540. I don't mind as getting into the minutiae of machine workings in one of life's pleasure as far as I'm concerned. So last nights challenge was this control knob.....capture.jpg

Again a slight mangling from a previous owner has disguised the means by which the knob is fixed to the shaft. On one side it looks like a hex socket grub screw, only I can poke a 1mm pin all the way through the knob and till it pokes out the other side. If it is a grub screw (with a hole in it) I cant find a key that seems to fit. It might be a roll-pin but when tap it with a pin punch it doesn't show any willingness to budge.

I might need to get more brutal but before I do I thought I'd check with others on here that usually know from previous experiences. Any thoughts please ?

Dave S06/12/2021 13:01:40
370 forum posts
90 photos

IIRC it’s a taper pin. So will only come out one side.

I can have a look tonight - mine was off not very long ago.


Chris Crew06/12/2021 13:12:29
208 forum posts

Gerry, It's definitely a roll pin on mine. It is not a taper pin on, at least, my machine as suggested by Dave S although that is not to say all machines will be identical. I have just been out to the workshop and tapped it halfway out and back in again just to prove it for you.

Mark Rand06/12/2021 16:18:27
1275 forum posts
28 photos

Mine are held by taper pins!

Dave S06/12/2021 17:06:16
370 forum posts
90 photos

Taper pins on my controls, presumably so you can’t put them on 180 degrees out.


Don’t know if a roll pin in a taper hole would form itself into a taper?


gerry madden06/12/2021 19:54:48
252 forum posts
132 photos

Thanks chaps for your help. It turned out to be a roll pin like Chris's model. Eventually with some unkind drifting it began to move and reluctantly came out, dry as a bone and clogged with dust and corrosion. After that it was just a simple matter sliding the handle off its hour later that was done too.

It was an ugly sight under the valve cover but thankfully just cosmetic...... but its all going to come apart anyway


By the way, if anyone out there is interested in me giving a summary of my refurbishment on this 540 as it goes along just let me know and I'll try to do that.


Chris Crew06/12/2021 21:16:30
208 forum posts

Gerry, Judging by the electrical gear on the front panel your machine looks like mine, circa 1971. When I acquired it, getting on for twenty years ago now, it was in about the same state as yours too. The table would not oscillate and no amount of penetrating oil, as recommended by the real J&S in Leicester because I called their technical support department at the time, would free it. The only thing to do was to strip it down completely and excavate the shuttle valve, thoroughly cleaning everything as I went. I actually had no idea what I was going to find and I think, if my memory serves me correctly, it looked pretty complicated with all the hydraulics etc. BTW, the table is held down by gravity alone. Once you have disconnected the push/pull rods it will simply lift off but it is very heavy and I advise a two man lift if you intend to do this. I did manage everything on my own but I was twenty years younger and fitter in those days and it was still a struggle. When I got the shuttle valve out I found it was absolutely seized solid. There must have been some water in the hydraulic oil and with the machine standing unused, for I don't know how long, the oil had congealed and corrosion set in. To free the piston I had to hold the valve in the vice, put a brass rod against and smack it hard with a hammer several times and it eventually shifted. I was expecting to have to replace the valve but the piston and cylinder didn't look too bad when cleaned and lubricated so I decided to replace it into the machine when I re-assembled everything. It has worked perfectly well for twenty years although I think the machine has had an hydraulic oil change since and I keep running it for a few minutes occasionally to make sure the oil is circulated as it doesn't get used in anger all that often. I don't know the level of your skill but don't be put off by what you find under the table. Maybe ignorance is bliss in my case but I tend not to be afraid of taking things apart and simply reversing the process after having a 'look-see' and cleaning everything.

Edited By Chris Crew on 06/12/2021 21:19:37

Nigel McBurney 107/12/2021 09:07:38
1000 forum posts
3 photos

The handwheel for the cross feed has a central lube nipple,it is for OIL not grease,a J & S servive engineer told me once that countless owners had feed problems all due to using grease in error.

Dave S07/12/2021 10:34:52
370 forum posts
90 photos

Mine is around 1960 judging by the build plate on the oil tank.

Some photos here **LINK**


gerry madden07/12/2021 17:40:54
252 forum posts
132 photos

Nigel, yes you are right. Most of the grease nipples on the 540 should be fed with oil. I would imagine that most machines have been abused in this respect at some time or other. I found after removing a nipple on my elevation wheel I couldn't blow air through the hole. I had to press the brass bush out to find out that grease in the passages was the cause of the "blockage". Still to get oil in a nipple one needs to use a gun, so I imagine pressure from that would displace the grease without too much difficulty, but at least now I know it was nothing more serious.

Chris, thanks for your guidance re the table removal. Mine actually moves nicely. I can even slide it by one hand without the pump running. I can also see all the ways are fully scraped suggesting no great wear. Regardless, the table will be coming off. I think I'm like you...I just have to take things apart and don't worry about not being able to rebuild. Where there's a will, theres a way.

One thing I do have is some patches of corrosion on the top of the table where the chuck sits. There is some on the base of the chuck too of course but I can turn that upside down to grind it. However the standard wheel will not reach the table. Its about an inch clear. What I thought I could do is fit an oversize wheel (after checking speed limits of course) then I will be able to grind the table flat and remove the pitting. Is there is another way ?? I cant think of one other than have it machined when the table is off the machine.....but this wont be anything like as accurate. Any thoughts ?

Dave S - great info.

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