Meddings Pacera oil seal upgrades???

[daxliniere]

Hey everyone,
First of all, a solid disclaimer; I know that a drill press is not a mill. But I've come to peace with it since a) I don't do much milling and what I do is light duty b) I don't have space/time/money for a mill and c) the Meddings uses angular thrust bearings, just like a real milling machine. And so...

The Meddings M4 drill press I bought was fitted with crossslides to give it milling capabilities. As part of the rebuild, I replaced the lower gearbox oil seal which had been leaking. The 24mm ID seal with integral spring seemed to work really well for about 2 months, but I've noticed that it's now ******* out oil and the only thing I can think is that it happened after I did some milling with it.

Is there another kind of oil seal I could use for this task?


Thanks in advance for any advice.

All the best,
Dax.

 

[Sergei Slovenija]

Oil seal with 2 ribs. Or remove the spring and twist a little more, reducing the diameter of the spring-ring.

I don't know how your spindle works, switching to grease instead of liquid oil will get rid of the drips.

 

[daxliniere]

Oil seal with 2 ribs. Or remove the spring and twist a little more, reducing the diameter of the spring-ring.

Cool, thank you, Sergei. I'll look up that type.

I don't know how your spindle works, switching to grease instead of liquid oil will get rid of the drips.

I misspoke, sorry! The oil is actually from the bottom of the gearbox. (I've updated my original post.)

 

[Brad93]

It only has

Hey everyone,
First of all, a solid disclaimer; I know that a drill press is not a mill. But I've come to peace with it since a) I don't do much milling and what I do is light duty b) I don't have space/time/money for a mill and c) the Meddings uses angular thrust bearings, just like a real milling machine. And so...

The Meddings M4 drill press I bought was fitted with crossslides to give it milling capabilities. As part of the rebuild, I replaced the lower gearbox oil seal which had been leaking. The 24mm ID seal with integral spring seemed to work really well for about 2 months, but I've noticed that it's now ******* out oil and the only thing I can think is that it happened after I did some milling with it.

Is there another kind of oil seal I could use for this task?


Thanks in advance for any advice.

All the best,
Dax.

The meddings have a single angular contact bearing at the bottom of the spindle and no way of setting any preload. The pressure of drilling does that. So I doubt it will be much good for milling. They're flexible as you like too. It's a drill at the end of the day

 

[daxliniere]

It's a drill at the end of the day

Sure, Brad, I know this, hence my disclaimer and explanation.
So far this is what I've done with it, so it is capable for my purposes. This was about 3 or 4mm thicker. Surface finish came out great with an average carbide end-mill in the Jacob's chuck. (ER collet chuck is in the mail.)

My question is very much about how to make this machine as good as possible

 

[Agroshield]

The standard seal sounds like what is called a 'single lip seal'. The alternative suggested by Sergei is thus called a 'double lip seal'.

The efficacy of sealing depends on the condition (roundness and smoothness) of the shaft as much as it does on the rubber.

What oil did you put in the gearbox? Is it approximately what the manufacturer specifies? Was it a name brand, good quality seal?

 

[Brad93]

The meddings takes custom seals which are no longer available.

 

[Smouser]

Unfortunately I do not know of a great solution. As you know the original oil seal is not made anymore. Which leaves you with a choice of 25mm ID seals or 25mm ID seals. If I remember correctly the shaft is around ~24.90mm or so.

I have got two M4 drills and one is running a 25mm seal and the other a 24mm seal. The one with the 24mm seal leaked pretty badly when I fitted a 25mm seal so went to the 24mm seal.

Because the 24mm seals are 'stretched' they sometimes do not last very long before they start to leak.

Possibly the only long term solution is to turn the shaft down a little in a lathe so a 24mm seal fits better?

 

[bricol]

Is the shaft hardened? A sprung oil seal will wear a groove in a "soft" shaft.

Your seal may be leaking simply due to excessive movement if there's no preload on the bearings.

 

[Brad93]

could spray the shaft then machine it to 25mm.

 

[Dieselman 63]

Don’t mill with it. You’ll knacker a good drilling machine. Mill with a mill. The Morse taper isn’t designed for the forces of milling. Like @Brad93 saye it’s only got one angular contact on the spindle nose. I predict tears and lost pennies.

 

[daxliniere]

Actually, guys, I found the problem today. Turns out oil wasn't leaking from anywhere I had expected. As you can see, the oil seal is dry, so it has been leaking from the oil seal boss gasket. It looks hand made and is probably from the wrong material. I suspect the reason the leak started so aburptly is that the gasket got completely saturated and started wicking the oil out instead of holding it in.
You can also see some remnants of another gasket (orange in colour) that wasn't removed properly.

I've got a bit of Flexoid that I can cut with my CNC, but since it's paper-based, I'm not sure it's going to fix the problem. I have some 1.2mm silicone sheet and could probably work out how to machine that on the CNC, too. (probably a sandwich between timber)

Otherwise, I guess I could wrap a nitrile glove around the whole thing and just poke a hole for the spindle shaft to go through. It sounds ridiculous, but I bet it would work.

I can also see that it is leaking a little oil from the edges where the top and bottom parts of the gearbox chassis meet. Not sure what to do about that yet, but I think a CNC-cut paper gasket should do the trick.

Any thoughts?

 

[Smouser]

On mine I just used instant gasket maker.

Something like this https://www.halfords.com/motoring/t...airs/granville-instant-gasket-40g-174675.html

 

[Sergei Slovenija]

Actually, guys, I found the problem today. Turns out oil wasn't leaking from anywhere I had expected. As you can see, the oil seal is dry, so it has been leaking from the oil seal boss gasket. It looks hand made and is probably from the wrong material. I suspect the reason the leak started so aburptly is that the gasket got completely saturated and started wicking the oil out instead of holding it in.
You can also see some remnants of another gasket (orange in colour) that wasn't removed properly.

I've got a bit of Flexoid that I can cut with my CNC, but since it's paper-based, I'm not sure it's going to fix the problem. I have some 1.2mm silicone sheet and could probably work out how to machine that on the CNC, too. (probably a sandwich between timber)

Otherwise, I guess I could wrap a nitrile glove around the whole thing and just poke a hole for the spindle shaft to go through. It sounds ridiculous, but I bet it would work.

I can also see that it is leaking a little oil from the edges where the top and bottom parts of the gearbox chassis meet. Not sure what to do about that yet, but I think a CNC-cut paper gasket should do the trick.

Any thoughts?

View attachment 356724 View attachment 356725 View attachment 356726 View attachment 356727 View attachment 356728

Why, explain to me, use CNC to make an ordinary flat gasket ??? Oh times... I wouldn't be surprised if plumbers soon start carrying around a miniature CNC machine to cut plain gaskets to exactly fit a customer's individual faucet .

 

[daxliniere]

Why, explain to me, use CNC to make an ordinary flat gasket ??? Oh times... I wouldn't be surprised if plumbers soon start carrying around a miniature CNC machine to cut plain gaskets to exactly fit a customer's individual faucet .

Because I have the tool and by the time I finish measuring up the part, I might as well punch it into Fusion 360. I've gotten pretty quick with it and it means that I'm going to turn out with exactly what I want and don't have to rely on cutting it out by hand.

 

[daxliniere]

On mine I just used instant gasket maker.

Something like this https://www.halfords.com/motoring/t...airs/granville-instant-gasket-40g-174675.html

Good call on that. I guess it makes it a little harder to get into if you ever need to get inside again, but good to know it works.

 

[daxliniere]

Tell me that gasket doesn't look great, though.

Made from my daughter's old silicone bib.

 

[Turbo]

A bit of gasket paper with a smear of oil resistant instant gasket or RTV should be sufficient to seal that.

That flange looks like it locates the bearing behind it so your fancy silicone gasket will likely be too thick and allow some end float in that shaft!

 

[RichardM]

I'd put a smear of blue Hylomar on it and the screws if they go all the way through the casing.

 

[Agroshield]

It's good to look at the parts with an open mind before deciding on a solution. That means ignoring what others in the past have done and going back to first principles.

The flat surface of the underside of the gearbox is unmachined - rough cast straight out of the mould. Have you ever seen a gasket surface in another application that looks like it does? Look at the junction between the head of your car and the inlet or exhaust manifold. Remove the plain cover adjacent to the aluminium one and look at the mating surfaces.

Any gasket at the junction we are looking at would be useful for cushioning only. The seal will/should be on the machined cylindrical part of the aluminium against the machined cylindrical part of the bore into which the bearing goes.

As RichardM says, a light coating of hylomar should be all that is necessary. Again, to reinforce what he says, if the three holes for the retaining countersunk screws go through into the oil-bearing part of the gearbox, it would be a benefit to smear the threads of them with the same goop to stop oil wicking down that path. If the threaded holes are blind, this is not needed.