Startrite Mercury 2 10 speed restoration

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J-G

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I said that I only had Tufnol at 10mm thick but thinking 'outside the box' I also have Acetal Rod on the shelf in various diameters - including nominally 28mm which is 1.1023 though it is in fact a little 'oversize'.

Acetal is an industrial plastic just like 'Delrin' but Delrin is DuPont's trade name for it.

Realizing this made me think to break out my Gear Hobber which I haven't needed to use this year since I've been getting to grips with larger gears on my new (to me) CNC machine.

The result is that I have made you a length of 20T gearing which I can cut down to a pair of ½" thick gears.
20T 20DP Acetal.png


I've made the bore 10mm because that is a standard arbour I have for my Hobber and I assume that you have the means to bore out to the diameter you need - that also makes more sense because you also have the spindle to fit it against. No matter how accurately you measure the spindle it would still be best for you to do the final fitting empirically.

Send me a PM with your address and I'll get them cut to width and pop them in the post.
 
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RichardG

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J-G that’s amazing, thank you. Yes, I can bore them out to size. PM on the way.
 

RichardG

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I have now stripped everything down, removed all the bearings, and found no more obvious issues which is good news.

I will now degrease each part and carefully check before reassembly. The first item was the base, pole and frame/casting. I like machines to look old so wherever possible try and keep the original paintwork and just wax to stop rusting.

I degreased the pole and then wrapped in a strip of towelling before soaking in white wine vinegar overnight. The yellow towel turned red as the rust was dissolved.
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I then mounted on the lathe to clean and lightly rub down. My lathe takes 36 inches between centres and the pole is 40 inches but I managed to squeeze it on by moving the motor and tail stock outboard of the mounting on a narrow stand.

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It cleaned up well and after waxing mounted to the cleaned and waxed base. After removing all the bearings the cast frame got the same treatment.

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When you compare the engineering on the 5:1 reduction box to the main drill you wonder if they were done by different departments, seems much heavier engineered, I wonder if the core design was taken from another Startrite product? The standard shaft and shaft bearings are small compared to the ones used at the head now.
F077A986-C656-469F-A908-9261C0EFAE74.jpeg

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The 2 top left are head/gearbox with the thrust bearing. The smaller 2 are standard shaft bearings, these normally being supplemented with a thrust bearing in the standard drill. The final two are the pulley shaft bearings.

sizes are outside/inside/thickness

main: 52mm / 25mm / 15mm
pulley: 47mm / 25mm / 12mm
shaft: 1 3/8“ / 5/8“ / 11/32”
thrust: 45mm / 25mm/ 14mm

I was going to replace them all but the only one running rough was the thrust bearing and now all the crud has been removed it seems fine. Is there any foolproof way of doing a bearing check?
 
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deema

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Yep, bin them and buy new! They are metric bearings so after all the effort don’t skimp as they are very cheap. Buy high quality SKF, FAG or similar.
 

RichardG

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Yep, bin them and buy new! They are metric bearings so after all the effort don’t skimp as they are very cheap. Buy high quality SKF, FAG or similar.
Well, I’m trying hard now to be more environmentally aware and not binning stuff just because it’s the cheap and easy thing to do. If the bearings are ok then I’d like to reuse them if at all possible but if there’s no way of assessing I guess I’ll have no option.
 

deema

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I understand and being originally from Yorkshire would rather not spend a penny more than necessary. I believe most if not all bearing company’s recommend not to reuse bearings. The issue is that when removing them the balls can cause microscopic indents on the races which causes when in use galling leading to the bearing failing. If this happens you can end up ruining more than the bearing. I’ve seen a few journals that have been scored / ruined following a bearing failure.
You need to be very careful installing press fit bearings to avoid denting the races or again new bearings can fail very quickly.
 
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RichardG

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I understand and being originally from Yorkshire would rather not spend a penny more than necessary. I believe most if not all bearing company’s recommend not to reuse bearings. The issue is that when removing them the balls can cause microscopic indents on the races which causes when in use galling leading to the bearing failing. If this happens you can end up running more than the bearing. I’ve seen a few journals that have been scored / ruined following a bearing failure.
You need to be very careful installing press fit bearings to avoid denting the races or again new bearings can fail very quickly.
Thanks for this, I'll replace them all.

The metric bearings are easy, the imperial ones slightly less choice but I can't find the thrust bearing at the moment, the standard seems to be 47x25x15 but I've checked and can't get a 47mm in...
 

RichardG

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Have now ordered some SKF bearings, couldn’t find a replacement thrust bearing at a sensible price though. I did find a company who specialises in old stock bearings who could supply at £43.50 (Hoffmann Bearings) but I think the old one is good enough at that price.

The gears from J-G did arrive today and after boring them out using a reamer, pressed the bushes in and did a trial fit, looks perfect, many thanks to J-G for doing this👏

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Final job is to turn a new pinion mount from some silver steel. The old one broke either causing the failure or as a result of the failure. I had hoped to press out the centre as it appeared to be made in two pieces but couldn’t shift it. Perhaps it was pressed on whilst hot?

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J-G

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Good to hear that they fit OK. I hadn't appreciated that they were part of a planetary gearing system though. That means that the potential stresses are reduced which will be beneficial as far as using Delrin/Acetal is concerned.

As far as the thrust bearings are concerned, --- I'm thinking well outside the box now --- could you make a 'housing' for a slightly smaller OD & Thickness? - Looking at [Simply Bearings] they have 42 x 25 x 11 FAG at £12.53 + VAT and I assume that because it is a simple three piece unit the 25mm ID is the imperative dimension so if you could make a 'washer' 45mm OD & 3mm thick with a 25mm bore and a 'ring' at 45mm OD, 42mm bore and 11mm thick - or some modified combination that positions it central with the shaft. It's a compromise but may well do the job and bring it in line with current bearing 'standards'.
 
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RichardG

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I did actually buy that very bearing with the same thought in mind, I also wanted to compare new versus old. The thrust bearing shaft has has a threaded collar which I presumed was to preload the thrust bearing after assembly but it may be to accommodate different thickness bearings? I’m going to do a dry run re-assembly using the old bearings to work out what drifts I need and the best order to avoid putting any load on the new bearings so I will try this out. I may be able to use half the old thrust bearing as the washer...

478ED71F-3A8D-49F2-8E97-691517459A61.jpeg
 

RichardG

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Have now turned a new pinion pin and a bearing drift.

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Replacement bearings arrived from Bearingsrus who were cheaper than other suppliers and still gave good service. I had to use seiko KSM for the imperial sizes.

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I also turned a 3mm spacer so I could use the new thrust bearing which is smaller than the original but noticeably smoother.
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Using the old bearing I did a trial run to ensure I could get it all together without putting any strain on the bearings.

The pulley bearings were easy as they have 2 spacers fitted which allows you to drive both in together without putting any strain on the lower bearing. The top bearing was left slightly proud when I dissembled so I copied. The grub screw fix’s the outer spacer in position. I heating the casting up using a hot air gun and I could have almost pushed the bearings in by hand.

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The imperial spindle bearings were next and went in easily so didn’t take any pictures. The reduction gearbox assembly is next.
 

RichardG

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I have finally managed to start on this project again and assembling the quill bearings. These were all an easy push fit. The bearings in the reduction gearbox needed a bit of thought in the pressing order but again went in fairly easily, unfortunately I forgot to take any pictures!

I then pushed the quill back into head casting and was gob smacked to find a lot of play. I measured this as one thou fully extended with my dial gauge when I bought the drill but now it’s all cleaned up its more like 10 thou which is worse than my 30 year old Clarke drill.

First here are some shots of the casting and quill.

CA084742-C9FB-4CFC-B61D-B2C060B9CBDE.jpeg C5344B07-82F4-444F-AC1B-10DB157BF4CA.jpeg CDE7F7DF-6047-4971-BA45-9A5E626A7369.jpeg

My first though was to drill through where the red dots are shown and insert some brass grub screws and thread lock to hold in place?

I then tried some steel shim stock and manage to insert a 0.05mm shim on the bottom bearing and then bent over to stop it falling out, I couldn’t get anything in the top bearing. This completely solves the problem but seems a bit of a bodge? Is it going to wear the quill? Would it be safer/better using brass shim?

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Any other solutions that would be better?

Thanks

Richard
 

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