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Colchester Student Mk1 Won't Start

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Richard Kirkman 106/06/2020 19:36:42
237 forum posts
512 photos
Posted by Freddybear on 06/06/2020 17:54:47:

I replaced the bearings and the seals. ( and I seem to remember there is a gasket at the rear too).

However. I did have the entire headstock stripped at the time. Also I was sick and tired of all the oil leaks everywhere

Incidentally, I also bored my wormbox true and bushed it. Action is much more positive now.

Yes, I've replaced the gasket already and it's holding fine. It's just the seal that's leaking.

Phil, this stuff?

Filler

Sealent

Herman van der Merwe06/06/2020 19:55:32
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128 forum posts

Did you polish the shaft that goes through the oil seal before you installed it? It seems it is weeping past the seal on the shaft.

Phil Whitley06/06/2020 20:02:54
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1206 forum posts
145 photos

Thats the stuff Richard!

Richard Kirkman 106/06/2020 20:13:48
237 forum posts
512 photos
Posted by Herman van der Merwe on 06/06/2020 19:55:32:

Did you polish the shaft that goes through the oil seal before you installed it? It seems it is weeping past the seal on the shaft.

Nope, just cleaned with a cloth, no abrasives were used

It's coming out through the outer bit. Pretty much where i carved a channel in. Exactly where you told me to fill it and I didn't. I should have listened. I'll fix it

If you look carefully in the top right, its definitely leaking from there. That's the exact spot

img_20200606_184955.jpg

Herman van der Merwe06/06/2020 20:55:21
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128 forum posts
Posted by Richard Kirkman 1 on 06/06/2020 20:13:48:
Posted by Herman van der Merwe on 06/06/2020 19:55:32:

Did you polish the shaft that goes through the oil seal before you installed it? It seems it is weeping past the seal on the shaft.

Nope, just cleaned with a cloth, no abrasives were used

It's coming out through the outer bit. Pretty much where i carved a channel in. Exactly where you told me to fill it and I didn't. I should have listened. I'll fix it

If you look carefully in the top right, its definitely leaking from there. That's the exact spot

img_20200606_184955.jpg

As we would say in SA ... Eish! It means something like: "Oh no that is terrible and there is no solution"

You will have to pull the seal and buy a new one. You cannot reuse an oil seal. You also need to polish the shaft where the lips fit to a mirror finish to ensure that the shaft does not sand away the lips.

With oil seals there are no short cuts ... you need to ensure everything is perfect before installing an oil seal. Please put some of the sealant I recommended on the outside of the new seal and lots of oil on the whole shaft before installing the seal and then the shaft.

Edited By Herman van der Merwe on 06/06/2020 20:56:23

Edited By Herman van der Merwe on 06/06/2020 20:56:56

Richard Kirkman 106/06/2020 21:07:28
237 forum posts
512 photos

I've ordered a new seal, I'll polish it till I can see myself. It'll probably be a week before it arrives.

The plus side is I'll have to drain the headstock, so I'll be able to try to clean the sight glass!

Richard Kirkman 108/06/2020 16:46:54
237 forum posts
512 photos

Just finished taking the oil seal and shaft back out. Polished the shaft up nicely. It's brighter in person, the camera doesn't quite do it justice.

The seal came out quite easily. I would have been tempted to reuse it, but I have ordered another so I'll wait for that. I think it came out so nicely because there was oil in the hole, so it slid easily. Looking in it after you can definitely tell that it leaked through the outside. Although it may have leaked through the shaft as well.

The shaft seems to have a little bit of pitting on it, I think it's minor and won't matter, but your thoughts and opinions are welcome as always. It's around where the seal is, so maybe it needs dealing with? I don't particularly know how tight it needs to be.

The sight glass definitely needs a good clean, but I can't really get to it without taking the main spindle out. Luckily that's a lot easier for me than it is for Herman! So, I may take the spindle out and give it a go.Undecided yet

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Howard Lewis08/06/2020 20:59:00
3288 forum posts
2 photos

When you install the new seal, ensure that the lip is away from the track made by the original seal. 1/8" will quite sufficient (That is the advice given by engine manufacturers ).

In that way, the new seal will lap itself the shaft, and not running on a worn shaft with loss of lip/shaft intereference and sealing pressure

Catch 22 is making a dolly, a few thou smaller in diameter than the seal body, so that you drive on the metal body of the seal to install it. But, for that you need a functioning lathe!.

Howard

Herman van der Merwe08/06/2020 21:03:53
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128 forum posts
Posted by Howard Lewis on 08/06/2020 20:59:00:

When you install the new seal, ensure that the lip is away from the track made by the original seal. 1/8" will quite sufficient (That is the advice given by engine manufacturers ).

In that way, the new seal will lap itself the shaft, and not running on a worn shaft with loss of lip/shaft intereference and sealing pressure

Catch 22 is making a dolly, a few thou smaller in diameter than the seal body, so that you drive on the metal body of the seal to install it. But, for that you need a functioning lathe!.

Howard

It is for this reason I recommended that he replace the seal with a double lip seal. Just make sure as @Howard said that the lip does not run on the shaft in the same location as where the old seal lip was. Your shaft is badly eaten away!

Your polishing will help drastically! Good job!.

Put the RTV silicone around the whole bearing's outer edge and hammer it in. A correctly sized socket works a treat as a dolly. Use acetone or thinners to clean the housing where the seal will fit before installing so as to ensure that the silicone will bond to the metal.

Edited By Herman van der Merwe on 08/06/2020 21:05:31

Phil Whitley08/06/2020 21:10:30
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1206 forum posts
145 photos

I think you mentioned earlier that you replaced the single lip seal with a double lip? If so this would put at least one, and possibly both lips in a slightly different place on the shaft, so the pitting/scoring may not be in the lip area any more! The reason not to reuse seals is that a worn seal will never go back in the same place, and is highly likely to leak, and also the difficulty in getting the seal out without damaging it. You seem to have got this one out intact, and I would say this is a case where you might get away with reusing it, but in general, always fit a new one. Could you get a tin of spray brake cleaner with a long nozzle pipe and spray it into the sight glass, even WD40 might do a decent job of cleaning it. You can buy new sight glasses from Nipple shop (online).

Phil

Richard Kirkman 109/06/2020 00:17:19
237 forum posts
512 photos

Thank you Howard, Herman, and Phil.

Some valuable insight there. I hadn't considered that the single to double lip would make a difference, but it does make a lot of sense.

I think the pictures make the damage look worse than it really is.

As for the sight glass, the body filler won't arrive for potentially another week, so I may as well take the spindle out and have a good go at cleaning the sight glass. I need something that I can squirt in that will break up the thick muck, but I'm not sure what would be best. The filler may also come in handy If I want to fix any casting imperfections when I get around to repainting. Still practicing on the traveling steady, I'm almost happy with the finish.

Phil, I don't think I have a local nipple shop anyway. I'll just try to keep these ones

I'll try putting some window cleaner in and let it sit for a while. I may have some pipe cleaners I could try as well.

Oh dear! Now I've just though, if the spindles out maybe I should try to replace the final gasket too. I've opened a can of worms within a can of worms. Still better than being bored!

Richard Kirkman 109/06/2020 21:27:27
237 forum posts
512 photos

Fantastic progress today, I'm very satisfied with what I've done

I began by moving the lathe away from the wall and starting to remove the main spindle. It must be the 4th or 5th time I've taken it out now, so it was very easy.

Side note, Phil and Herman. If you decide to use the nitrile rubber gasket material you should know that it creates a very tight seal, almost sticks the two faces together, so it was a little bit of a struggle to get the parts off. But well worth the effort for it to not leak

Anyway, as I was taking it to pieces I saw the usual leaking spots. It drips out from below here, however, this could also be leaking from the main spindle where the casting is broken. Either way, I need to replace the gasket

img_20200609_125759.jpg

Looking at the back bearing cover housing there is definitely space for a ring of some sort to be placed, and there are grooves in the main spindle too. I am sure there must be some sort of seal here too since a little oil leaks out. But I can't find anything in the manual about it. Thoughts???

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Then I proceeded to remove everything else. I blocked the bottom hole of the sight glass with a rag, then I used a pipette to repeatedly fill it with glass cleaner. I managed to find some pipe cleaners in my grandpa's old toolbox so that was a great help. It was tricky, but maneuvering them inside helped to clean it out. I let it sit, then cleaned, then filed it back up and let it sit many times. And I am very pleased with the result. Looking closely it seems like there is a crack on the inside of the glass, or maybe a scratch, but it doesn't go all the way through and I'm not quite sure how it got there, so I'll leave it.

img_20200609_161439.jpg

Then I moved onto the removal of the forward-reverse spindle. This stopped pretty quickly since its held in by a circlip which I need 90-degree circlip pliers for, but I only have straight ones. So I'm stuck for now, however, I have ordered some. Click and collect from Screwfix so they'll be ready soon I hope.

img_20200609_182139.jpg

Looking at the manual of the lathe, there is a bearing and an oil seal on this shaft, so I will replace both.

This means ordering more parts and waiting a while, so I will take the threading gear box to pieces again and clean the sight glass in there the same way. I'll also take the tumbler arm off again and put that back on properly since after I played with it it has started leaking a little.

While I was waiting between the sight glass marinading I painted the wall behind the lathe white. I'll do a second coat tomorrow, but It's looking a lot brighter. It should make lathe work a bit easier.

The threaded hole in the headstock used for mounting the splash guard in my lathe has been used for a chuck guard. I don't tend to use the chuck guard as it just gets in the way, So I'll take it off. I will also try to get the splash guard from Tracys lathe and fit it to mine if possible, but postage may be an issue, and that's if she ever gets back to me!

Plenty to do

Herman van der Merwe09/06/2020 21:47:56
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128 forum posts

After your polishing exercise I went to look at the condition of my shafts where the oil seals are. Not too bad, but definitely some wear.

I measured the depth of the housing and found that while the breadth of the seal is 9,2mm, the recess is more than 13mm. This made me check if I could fit two narrow seals instead of only one. Yep, it was possible.

I will replace the two seals with two thinner seals on each shaft.

To make my life easier I decided to sit down today and compile a spreadsheet of each bearing, oil seal, O-ring and circlip on my lathe.

Here are the details of the two oil seals in the headstock.

Edited By Herman van der Merwe on 09/06/2020 21:50:12

Herman van der Merwe10/06/2020 08:19:46
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128 forum posts
Posted by Richard Kirkman 1 on 09/06/2020 21:27:27:

Anyway, as I was taking it to pieces I saw the usual leaking spots. It drips out from below here, however, this could also be leaking from the main spindle where the casting is broken. Either way, I need to replace the gasket

img_20200609_125759.jpg

Looking at the back bearing cover housing there is definitely space for a ring of some sort to be placed, and there are grooves in the main spindle too. I am sure there must be some sort of seal here too since a little oil leaks out. But I can't find anything in the manual about it. Thoughts???

img_20200609_182139.jpg

Looking at the manual of the lathe, there is a bearing and an oil seal on this shaft, so I will replace both.

I would definitely fix the casting. You need even pressure on the flange to get a good seal. You can either braze it or use metal epoxy. Me? I would use metal epoxy as these days the resulting material is better than the old steels.

Yes, the second seal I mentioned is inside this bearing. There is no bearing. The cast iron flanged unit is the bearing.

Good work on the sight glass!

Herman van der Merwe10/06/2020 09:46:30
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128 forum posts

There should be no seals in the back bearing cap. Notice the notch in the lip? That is the return slot for oil to flow back into the bearing. Basically the oil is spun around in the cap, gets caught by the grooves and drips back into the bearing. Some shafts I dealt with had what is something like normal felt (real wool) cut into a strip and with ends located over the notch. You can try this if there is a lot of oil running from between the spindle and the cap.

Richard Kirkman 110/06/2020 10:48:58
237 forum posts
512 photos
Posted by Herman van der Merwe on 10/06/2020 08:19:46:

I would definitely fix the casting. You need even pressure on the flange to get a good seal. You can either braze it or use metal epoxy. Me? I would use metal epoxy as these days the resulting material is better than the old steels.

Yes, the second seal I mentioned is inside this bearing. There is no bearing. The cast iron flanged unit is the bearing.

Good work on the sight glass!

Thanks, Herman

I should be eventually getting a replacement flange, so I haven't bothered with trying to fix it. I'm not sure epoxy would be strong enough since the countersunk head has been pulled through, so it would need to be strong. Hopefully, I'll get the part.

Your explanation about the spinning oil grove makes a lot of sense so thank you again.

The circlip pliers are not going to be here today, so my dad borrowed some from work, hopefully, I'll be able to make them work. Only time will tell

Edited By Richard Kirkman 1 on 10/06/2020 10:49:20

Richard Kirkman 110/06/2020 13:42:09
237 forum posts
512 photos

Unfortunately, the circlip pliers didn't fit so I'll have to wait.

Meanwhile, the threading gearbox sight glass leaned up very well, although the paint from the words disappeared.

As you can see, it was cleaner than the headstock one, but now they're both fully clear. Or at least as clean as I want to get them.

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Then I did a second coat of paint on the wall. The wall now reflects the light much better, and it's the wall that the lathe sits against, so it's a big improvement. I can't have a white backsplash like Phil, so i'll make do with a white wall!

Now we're just back to waiting for parts to arrive...

The caps are past their delivery date, so I expect them any day now. As is the toggle switch. I have the new spade connectors but I'll wait till the wall has dried so I can tidy everything up

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Richard Kirkman 111/06/2020 21:18:54
237 forum posts
512 photos

Another productive day!

Firstly, I decided to replace the spade connector, which went okay. Nothing new, just strip and crimp. Caps will be replaced as soon as they arrive. Don't know when that will be. It seems to me that we only get post once a week these days.

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Then I went and picked up the circlip pliers. The circlip wasn't easy to remove, but I managed eventually. Then the shaft just slid out quite nicely.

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Pretty messy inside. Initially when I took this to pieces last time, I tried to clean up the inside of this through the slot at the bottom. i found some pins inside and I had no idea where they came from. Thinking about this more today, 3 months later, They must have been spare shear pins, but why on earth would they have been stuck up there with loads of gunk? Judging by the quality of the seal it can't have done it any good.

That's the pin I found in the pic below. But after I removed out the old seal.

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I managed to get the seal out without cutting into the shaft this time. I just drilled it and punched it till it came out. Quite easy

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Then the img_20200611_143009.jpg

The shaft came out quite easily but there was no sign of a gasket. Every other place has had a gasket in, but this one doesn't. It wasn't leaking, but I've made a gasket anyway, It can't harm.

img_20200611_151429.jpg

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Since I had access, I removed the forward reverse lever. It wasn't leaking but I thought i'd replace the leather gasket since I can't harm and I can make one tighter.

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Same as the last one, Glued to a bit of wood, then turned by hand

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It fits really nicely, much tighter than the last.

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Then I polished the shaft where the new oil seal is going to go.

I measured it to be 1 1/16 inside, 1 5/8 outside, 5/16ths thick so a new one that size has been ordered. Exactly the size you said Herman!

I would have loved to submit a picture for the cover, but my lathe isn't exactly in pieces to take a picture of, or painted nicely!

Back to waiting for parts to arrive. So I'm making some drawers and working on the lawnmower

Herman van der Merwe11/06/2020 21:39:01
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128 forum posts

Great job @Richard!

Your shear pins surely are a lot smaller than the ones on my lathe. Would you mind measuring the diameter for me?

Next time when you move a seal over a splined shaft (or vice versa) wrap some insulation tape over the splines to protect the seal's inner face. As you move the seal over the uncovered splines, these will cut small slots ruining the seal's inner sealing surface.

Herman van der Merwe11/06/2020 21:40:44
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128 forum posts

BTW what make and model is the small green lathe?

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