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Crunchy Cross Slide Pinion

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Trevanion

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I had noticed the cross slide on my CVA lathe had been getting progressively more crunchy when the handle was being turned so I decided to take it apart which was a bit of a palaver, I got to the pinion gear which seems to be where the noise and feeling is coming from, it sits inside a bore and meshes with another larger gear a hole into the apron. At some point, somebody has put three o-rings on the rear of the pinion and looking at the parts manual I think there should be what's called a "felt retaining washer" and a "felt washer" on there and no more information beyond that.

So my question to anyone who knows, what is the difference between a "felt retaining washer" and a "felt washer"? Also, what kind of felt do you reckon is best for this kind of thing? Or is there a much better alternative I should consider?

Unfortunately, I don't have any photos of the part, I reassembled the carriage without thinking about taking a photo of it. I'll probably take it back apart at the weekend to measure up the part and I'll take a photo of it then.
 

TFrench

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I feel the felt washer would be an oil retaining soft felt and the retaining one would be metal to keep the felt in place?
From a quick google, I would give RH Nuttall in Birmingham a ring - looks like they'll have what you need.
 

Trevanion

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TFrench":1rlmvglk said:
I feel the felt washer would be an oil retaining soft felt and the retaining one would be metal to keep the felt in place?
From a quick google, I would give RH Nuttall in Birmingham a ring - looks like they'll have what you need.
Ah, Good thinking Batman! There is a metal washer holding the o-rings in place which is in turn held in place with a circlip, so perhaps the metal washer is the "felt retaining washer".
 

novocaine

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the upgrade was to put a leather washer in place instead of felt. it lasted longer.
as suggested above, the retaining washer will be the metal washer you already have, you can pick up the felt washer for peanuts if you measure the ID,OD.

when you install it, soak it for 1/2 hour in oil first, the felt is only there to hold the oil, the oil acts as the seal.

if you find a leather washer (you can punch your own easy enough) soak it over night in oil.

now go check the rest of the shaft seals aren't packing rubber. :wink:
 

Trevanion

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Thanks Novocaine, leather might be a good option as I’ve got some good buffalo leather somewhere.

Do you think the washer needs to be as thick as the space allows on the backend of the gear I.E. tight between the two metal washers? Or does it need to be a slack fit :?

As far as I’m aware there’s no rubber anywhere else :lol:, although I did replace some of the cork bed wipers which were worn out and allowing dwarf to get under with a silicone rubber instead, whether that was a good idea or not I have no idea but I had the stuff to hand. They work well at keeping the dirt out but I suppose in also works well at keeping the dirt in.
 

novocaine

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it should be a tightish fit to hold the oil against the surfaces. for a leather washer I'd have thought about 0.5-1mm oversize to allow for some compression but it not locking up the shaft, for a felt washer a bit more as the felt compresses. both are service items that will need inspecting every couple of years and a splash of oil when you remember.
My boxford needs a couple of new seals on the compound at some point (looking a bit thin on the last inspection), they are card/felt. send me the dimension and I'll see what I've got in the washers box, assuming I can get back in the workshop and find the tin they are in.
 

Trevanion

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Right, I've had the carriage apart today and I've got the pinion back out and took a photo and some measurements. The teeth on the pinion looka bit pitted and rough but they're actually quite smooth.



Distance between washers: 6.05mm / 15/64ths
OD of Bore: 25.3mm / 127/128ths (Definitely wasn't an inch)
OD of Pinion between washers: 17.4mm / 11/16ths

So I'm guessing I need a felt or leather washer that's 25.4mm / 1" in diameter for compression, with an ID of 17.4mm / 11/16ths and a thickness of 6mm?

I could get 6mm felt sheet pretty easily but I think I'd have to make two 3mm leather washers to fit there.
 

novocaine

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that's a bit thicker than I was expecting. :)
perhaps stick with felt for that. normally with leather you would form a 6mm tube by pushing it in to a form of slightly oversize dimensions. we use to do this for pump cups and the like. bit to much material needed to do that though, so felt seems like the better option.
 

Trevanion

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TFrench":1tnttxoh said:
So did it fix it? :D
Only just saw this, sorry!

Well... Kind of? I made three 2mm leather washers and crammed them onto the pinion after leaving them soak in Tellus 32 overnight. It’s definitely helped but it’s still a little crunchy :x, I may have to live with it unless I can solve it proper. Perhaps my hand cut washers weren’t precise enough, perhaps the really odd sized and rather rare thrust bearings in the carriage are worn and are allowing some play? I honestly have no idea and I’m sprinting blind folded with ear plugs in.

The joys of old rather rare equipment where the company has been out of business for decades.
 

novocaine

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looking at those cogs I'd say the crunch was coming from the meshing of the gears. I didn't notice but did you say you'd clean out the gears?
if not can you get the whole assembly apart and clean it. you'll quite possible find a load of lubrication at the bottom of the casing with bits of shiny metal in.
 

Trevanion

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novocaine":o2uraevz said:
looking at those cogs I'd say the crunch was coming from the meshing of the gears. I didn't notice but did you say you'd clean out the gears?
if not can you get the whole assembly apart and clean it. you'll quite possible find a load of lubrication at the bottom of the casing with bits of shiny metal in.
The only way to get at the gears is to take the top of the carriage off so they're not easily cleaned, but the gear and it's corresponding mate look very clean and I couldn't see any visible swarf or debris in the bottom of the carriage. I suppose I could drain the oil and take the bottom plate off to see if there's any gunge.
 

novocaine

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Hairy fluff, if you've checked the splooge for curly ones and workshop glitter then I think you are right in that you'll just have to live with it. Theres a fair bit of pitting on the teeth, so it could be just that rather than bits of Detritus in the meshing. :)
 
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