How To Restore Syringe Filler?

[siamackz]

This WHS syringe filler is leaking.

 

Anyone with experience on restoring such pens? See pics. Does it come apart at that seam?

Edited September 16, 2018 by siamackz

[northlodge]

Definitely. There is a cork on the other end of the piston.

 

IIRC it friction fit rather than screw thread, but it is some years since I opened one.

[siamackz]

It screws out apparently, after some heat.

Edited September 16, 2018 by siamackz

[siamackz]

But, I have a new question. How will the cork I make fit in here. I’m confused because the part of the barrel in which the cork moves is tapering quite drastically. So how will it seal? Do I need to cut the cork in a special way? See pic:

[Flounder]

Perhaps the taper is on the outside only?

[siamackz]

Perhaps the taper is on the outside only?

That might just be it. Let me check. Thanks

[siamackz]

Ok, its done!

 

it seems the inside of the barrel is a consistent diameter even though the outside varies.

 

I tried making a cork seal first, but this pen requires a rather this walled seal as the seal bore diameter is 4.5.. and the outside diameter is 7.5mm with a wall thickness of about 1.5mm (making it a rather delicate seal, unlike vintage MBs or safeties). But, I did make a cork seal, I treated it with beeswax, etc. and then it cracked soon after I put it into the barrel. There went about an hour of work (because I do the cutting, drilling, and sand paper trimming manually).

So, I looked to O rings, but none of the sizes I had fitted inside the barrel. Also, i would need to stack up many O rings as the seal holder was quite a long one requiring a seal of length 9mm to fit properly. So, instead I cut a rubber seal that I had purchased a while ago from a plumbing store. This fit well and works.

Generous application of silicone gel, and done!

[Greenie]

Nice work. I use a lot of O rings. You really would only need one O ring that fits the plunger shaft and barrel. It can sit anywhere in the space for the cork seal. With O rings, there is no need for a longer seal that is typically seen/used with cork seals.

 

Depending on the diameter of the plunger shaft, you do not need an O ring that naturally matches the inner barrel diameter. One method that sometimes works, depending on the shaft size vs barrel size, is to take an O ring that is too small, stretch it on the the plunger shaft, and test the fit. A smaller one, stretched, will result in a thinner final ring that is tight to the shaft and a good fit to the inner barrel. Sometimes I line up two of them once I find a size that works.

 

This does not always work..... and in that case, your repair totally rocks and you deserve much praise!

[siamackz]

Nice work. I use a lot of O rings. You really would only need one O ring that fits the plunger shaft and barrel. It can sit anywhere in the space for the cork seal. With O rings, there is no need for a longer seal that is typically seen/used with cork seals.

 

Depending on the diameter of the plunger shaft, you do not need an O ring that naturally matches the inner barrel diameter. One method that sometimes works, depending on the shaft size vs barrel size, is to take an O ring that is too small, stretch it on the the plunger shaft, and test the fit. A smaller one, stretched, will result in a thinner final ring that is tight to the shaft and a good fit to the inner barrel. Sometimes I line up two of them once I find a size that works.

 

This does not always work..... and in that case, your repair totally rocks and you deserve much praise!

Thanks for the encouragement Greenie, and the tip too. I need to order an assortment of O ring sizes