Original PacificMeister Build Leak Issues - Any Solutions?

I am at a bit of a dead-end mates! My build is the classic PacificMeister MastClamp/Tube/SealMount with the SSS 56104 500kv motor + Neugart PLE 40 5:1 reducer. Like others, I have had persistent leaking issues in the SealMount area. Has anyone found a sure-fire solution to this problem?

Any help or tips are greatly appreciated!

Not cool indeed,
I haven’t done a dynamic test yet with mine just static, maybe you have too much oscillation in your shaft and that works on the spinnaker seals…the latter are even worn out by assembly and disassembly when the thread of the shaft rubs against the lips of the seals…( I noticed that mine were worn out after these numerous installation tests…) I also fix the seal mount and the mast clamp on the aluminium tube with M2.5 inserts placed hot ( 5 on each part).

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Thank Manu. I think you are right about the oscillation. And there may be another problem. The motor generates a lot of heat. But it is in direct contact with the metal tube (I use a metal spacer see my page HERE). The Neugart reducer, however, generates even more heat and has no means of dissipation. I suspect this is causing the sealmount to distort and add to the leaking issues.

HI Carl,
Amost ready with my build and this is a worry. The shaft couplers I bought are all not fitting tight.
When reading this thread I thought i would be interesting to see if Hiorth’s design could be combined with prints I made for th PM setug (duct, gearbox mount, etc).

This is what I came up with yesterday. Its not all there yet but it captures the idea. Its about 3cm longer than the orignal, to make space for the coupler and bearing retainer. It still has the M40 thread for the duct. But perhaps this needs to ditched to make it more robust. I would like to make it shorter too.

@hiorth Hi Hiorth. Borrowed your idea for my setup. I noticed in the text that you recommend steel as material. I am not sure if you were specifically referring to the bearing retainer ring or the whole assembly. The latter would be an issue for me haha.

In that material you have printed your seal mount, it can also be caused by a material that is not very resistant to heat such as PLA for example…

Shaft should be stainless
Housing and retainer plate would suffice with aluminium. If you are printing it keep in mind the retainer plate is under high axial load.

Thanks Hiorth. Will try to print the housing and test how that goes. Rest stainless are alu as you indicated

Cool! Looking forward seeing how it works out, we have been running a motor with this configuration for a year now, seems to be holding up well.

Thanks Manu. I am reprinting my sealmount in PET-G and will see if that performs better than PLA.

Looks interesting Marc. Thanks for sharing. I look forward to hearing how it works. The biggest challenge for me was alignment of the shafts and coupler.

You can use two seals between two ball bearings this results in better concentricity. And i would use the two seals because of different pressures in and outside the pot when it heats up and cools down. The shaft seals only work in one direction.

Thanks @Nibbler. This is what it looks like now. Did you modify the stock sealmount design accommodate your change?


Rotate the seal in the middle by 180°.


Exactly. I’d would rotate the seals too. If there’s enough space I would add a second bearing right next to the coupler. The problem is, when the diameter of your shaft is a little to small when fastening your coupler, you could have a bad concentricity. This could result in a leak.
I have another design. I can show you what I did when I’m at home.


I would submerge the unit 1m underwater for an hour and see if any water gets in as it is. If water gets in without the shaft spinning the seals could be leaking elsewhere. There are a few other ways to find where the seals are leaking.

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As promised the pictures.


Thanks @Nibbler. I’m not clear on what I’m looking at in the photos. Is the metal body your sealmount. And if so are you using an SSS motor with the Neughart PLE40?

Im using nema 23 with ss56104. And this is a separate housing for the sealings and bearings.
I have a thread regarding my buil. Have a look into it there are mor pictures regarding the drive :wink:

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HI Carl,
I modified the PM sealmount to fit the larger coupler, see my build

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Thanks @Marc87. Looks good! I look forward to hearing how your mod holds up in water tests.