Rescuing a 920 lathe!

[John RuddParticipant @johnrudd16576]

With the original motor running at 50 hz, 1400rpm or so, a 3 ph motor running at 25 hz would give the required 50 rpm spindle speed, with the motor running at some 700 rpm…There is of course a reduction in torque running slower motor speeds…..

I've not encountered any issue with my 9 x 20 other than a slippery belt caused by lubricant ingress…..( over zealous with the oil can…)

[Andrew TinsleyParticipant @andrewtinsley63637]

Thanks John!,

I will sort out the belt size and stick the nail in the wall! As far as the 710 or 730 bet is concerned. I am told on good authority that it is indeed the choice of electric motor and its mounting plate (feet). My belt is 910 on the Chester 920, yet the manual says it is a 930! It just depends on what motors are to hand on assembly.

Regards,

Andrew.

[RedsetterParticipant @redsetter]

My Chester 920 has the 710 belt. I imagine the longer one is even more expensive. If it is a question of motor mount which seems reasonable, surely the toothed belt would have to be longer as well? I know I'm being picky but I'm getting interested, and there isn't much info on the 920 forums which relates to the UK versions of these lathes.

Considering how many must have been sold, they are quite rare secondhand and you never hear of one being broken for spares.

[Andrew TinsleyParticipant @andrewtinsley63637]

Hello Redsetter,

You are quite correct in saying that a different length cogged belt is required if a 930 Gates belt is used. I am afraid off hand I can't remember the required size, but I have it noted somewhere if you really want to know the size!

Like you, I am amazed at the scarcity of second hand 920 lathes in the UK. I am not sure if I am correct, but I think they were only imported by Warco and Chester? Maybe they just didn't sell very well over here, unlike the USA! In their unfettled form they are a bit of a kit lathe and I am not sure how many people would have modified them to a high standard. It is a cheap lathe and I would think most were purchased by beginners, who would not have the experience to modify them. I would therefore expect that there would be quite a turnover of 920s, but apparently not!

I have never seen one being broken for spares. Although the one I have would be a good candidate, if I hadn't promised it to an impecunious friend, who is a novice engineer!

Regards,

Andrew

[RedsetterParticipant @redsetter]

I bought mine partly because I wanted a "reliable" belt drive rather than dubious foreign electronics, but in fact the belt drive is a weakness. I think they are good value if you know what you are doing, as the basic machine is quite sound. Some of the desirable modifications are not that simple for beginners and you would think that an improved version could be manufactured for very little extra cost.

Some of the non UK versions have interesting variations, such as tumbler reverse and some even have the hand wheel on the "English" side of the apron.

I have made a tumbler reverse and a long-travel tailstock for mine but so far have not felt the need for a four-bolt compound mounting, which is apparently essential. I suppose I am not taking deep enough cuts!

[Andrew TinsleyParticipant @andrewtinsley63637]

Hello Redsetter,

Your thoughts are much the same as mine. The lathe isn't bad, but for only a bit more effort on the manufacturer's part and suitable price increase, It could have been an excellent lathe!

I find the belt system to be a pain and a friend's much modified lathe was spoilt by this weird system. I am still in two minds whether to reinstate this or do something about it!

With regard to the 4 bolt compound mounting. my friend found that it wasn't strictly necessary as long as you put in some decent gib strips and located them (end on, a la GHT method). He did however finally do a much improved 4 bolt mod, which I think was purely a machining exercise to show off his skill. Whoever bought that lathe got a real bargain!

[RedsetterParticipant @redsetter]

Thinking about it, I did make new gib strips with better locating screws. I think the point about the compound mounting is that when the lathe was designed as an Emco in 1970? it was never intended for industrial rates of production using carbide tooling. Tell that to the kids today…..

[michael howarth 1Participant @michaelhowarth1]

My Chester 920 is my second. The first was a Warco which I bought secondhand and despite all the advice freely given about taking someone who knows lathes, I did not know any such person and ended up with a lathe with a badly worn bed down at the business end. In all other respects I found it to be a fine machine and after a fashion learnt to compensate for the worn bed enough to do some reasonable work. I did extend the cross slide travel, which probably wasn't really necessary but it did give me the opportunity to fit the Arc Euro anti backlash bearing set which was. I also made a 4 bolt compound mounting which reduced the top slide flexing on heavier cuts. As I have already mentioned the best mod of all was the inverter drive which transformed the machine and did away with the hassle of belt changing and belt breakages. That clutch knob can easily slip out of an oily hand and bang goes another fragile and expensive belt. This one had a 730 belt which was always a bit loose and could slip off the pulley with the clutch out. It would also run with a 710 but that was a bit tight until well run in. I also made a Steve Bedair type tumbler reverse but never actually used it in anger. I also upgraded the gib strip adjusting screws with the addition of bearings and this smoothed the cross slide action considerably.

Eventually the worn bed got the better of me as I became more critical of my own work and I sought to give it away to a youngster or other impecunious soul who maybe wished to get started but I found giving it away a lot more difficult than may be imagined. I heard a few "hard luck" stories which I just did not believe but eventually it found another home. I did take the inverter drive off and reverted it to original condition.

The features that I liked best about the 920 were its compact size and the threaded mandrel nose but these things were not easily found on other lathes. A Myford for instance was just a bit too big for my workshop. The ability to just screw on / screw off different chucks was a great time saver as well as an encouragement to use the right chuck for the job, & I was not prepared to give it up so I went for another 920 but found that Chester were then the only importers. I have of course refitted the inverter drive and apart from just the odd squirt of oil, the belt drive door is now rarely opened. Cosmetically, the Warco had the edge on the Chester which does have a few rough bits on the castings. It doesn't affect the running of the machine but I am sure that smartening up these areas wouldn't have put a great deal on the price.

Sorry to ramble on but the old hip is twingeing badly and keeping me out of the workshop so I had to find something to do.

Mick

[RedsetterParticipant @redsetter]

They were also imported by Axminster for a while, with the option of a slow-speed pulley attachment which bolted to the bracket plate somehow. It would be interesting to know what this was like, as I have never seen one.

[Andrew TinsleyParticipant @andrewtinsley63637]

Hello Redsetter,

I have the series of ME articles that someone on the forum kindly sent to me. They detail a low speed conversion with I think a kit that was available from Axminster. PM me if you want a copy!

So yes I should have remembered about Axminster importing the 920. Memory is getting bad!

Andrew

[Martin Hamilton 1Participant @martinhamilton1]

Their was also the Excel Pinnacle 918 lathe.

[Andrew TinsleyParticipant @andrewtinsley63637]

Thanks Martin!

That was a 920 importer that I didn't know of.

Andrew.

[Niels AbildgaardParticipant @nielsabildgaard33719]

An one hand mobile- video of an old lathe/man with VFD.

VFD drive is by far the best part of the shown man -machine combination.

I cut threads in direct drive and I have not spoiled electric motor yet.

**LINK**

[John HaineParticipant @johnhaine32865]

Can you fit link belts? Then you can adjust to fit.

As for using a vfd, if you get one with flux vector control the motor can develop full torque down to almost stopped. It may need a cooling fan though.

[Martin Hamilton 1Participant @martinhamilton1]

Just remembered their is also the Amadeal CJ 23B – 9×20 & CJ 23B x 750mm between centres, these 2 lathes come with 1200w motors + variable speed 100rpm – 1800rpm. Still sold today by Amadeal in London, these versions are made by Red Bull, don't know if this is the same maker that also makes the Chester 920.

[Martin Hamilton 1Participant @martinhamilton1]

The manufacturer should have read Real Bull.

[John RuddParticipant @johnrudd16576]

Posted by John Haine on 14/02/2018 07:58:49:

Can you fit link belts? Then you can adjust to fit.

Not that I know, the belt fitted is very narrow….5mm ?

[An OtherParticipant @another21905]

Hello, Andrew,

Did you ever get the info (bracket plate dimensions) you initially requested. If not, and you don't mind waiting a while (5-10) days, I will be dismantling my 9×20 for some other work, and will measure the plate. I also have a '9×20 Rebuild Manual' originally made freely available through the Yahoo group, which may be some help to you.

[Andrew TinsleyParticipant @andrewtinsley63637]

Hello An Other,

Redsetter did make some pretty accurate measurements for me. However if you are going to dismantle the area around the bracket plate, then you could probably make the measurements spot on. So the answer is yes please, I don't mind waiting in the least. I still have other things to sort out on the lathe.

I have all of the Yahoo downloads as well as the Grizzly and Chester manuals. The Chester one is surprisingly good too!

Thanks for the offer,

Andrew.

[An OtherParticipant @another21905]

OK, Andrew – I'll try to get round tooit ASAP

[John RuddParticipant @johnrudd16576]

Could I suggest, if An O is dismantling, it may be worth tracing round the plate and maybe locating the holes with a transfer punch type tool ( a pencil perhaps..) ? Then either mailing or scan/email….?

I'm not moving mine yet but when I do I could do what I suggested above if Andrew hasnt got the details by then?

( moving my machines is on the to do list ….)

[An OtherParticipant @another21905]

Hi, Andrew,

I stripped my lathe, and I have made a drawing. Some of my measurements differ slightly from those given by Redsettter. However, in general, nothing appears to 'drop-dead' critical. The holes which need to be cut can be sized from the items which fit into the holes – the belt tensioner, slow-speed clutch etc.

The plate shape is also not critical. The plate itself is quite crudely cut. The top edge and rear edge have been cut smoothly, but the lower edge looks as it has come directly from a flamecutter!

The curved part which overhangs the motor at the rear is only needed to support the lower of the two cover hinges. In fact, if you modify the machine for a VFD and three-phase motor, you could dispense with this plate and everything that is mounted on it completely. (You don't need the toothed belt, clutch, and belt tensioners with the VFD system).

I know you said you were not going the VFD route, but I did a write up with photographs of how I modded my machine, with a Moeller VFD, which was going to be sent to ME, but I had second thoughts after some of the comments I read. You can have that if you are interested. In my opinion, it turned a second rate machine into a first class job – I wouldn't be without it. (also never broken a drive belt in the 10 years since I did it)!

If you can PM me with an e-mail address, I can send you the file electronically. I can probably post it as a picture in the gallery, but I think an electronic file would be better, then you can view it in larger scale, or print it if necessary – let me know what would be best for you.

[Andrew TinsleyParticipant @andrewtinsley63637]

Hello An Other,

PM sent with my email!

Thanks again,

Andrew.

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