QUOTE (Gerry @ Dec 15 2005, 08:34 AM)
It would seem that this might be an opportunity to see the application of Francis's parts and technique by an independent evaluator - a non-repair person - and a review might be written covering ease of installation, completeness of instructions, overall evaluation etc.
Perhaps you should contact Francis to see if one of his working models could be obtained for such an evaluation.
Regards.
Gerry
Hi Gerry,
Thanks for your suggestion ! Who would you propose to install a "fountainbel" cartridge in one of Luigi's Vac-fills ? Would you do it ? Please let me know, I am open for any serious suggestion when Luigi agrees.
Hi Luigi,
In order to get the system launched I am willing to equip one of your V2 fillers with the fountainbel plunger rod cartridge for a plain 25.00 Euro's, shipping costs excluded.
You could also do it yourself, I wrote a "step by step" procedure for both the V1 & V2 versions with drawings showing how it is done.
As what concerns the other repair methods, I would like to say the following :
1- I would surely NOT go for the "add a sealing plug" method since it is only a temporarely solution, as already experienced by several collectors.
2- Restack the original sealing unit with new seals is surely a much better approach.
I have done this also on some of my V1 fillers with - at least initially- good results.
It is NOT neccesary to drill the old packing out on V1 fillers.
As I explained on the forum one can pull the old sealing unit out using heat & using a special nut.
Their is however a small drawback on this approach : The rubber rod sealing rings have to tighten both on the rod & on THEIR EXTERNAL DIAMETER to obtain a leakfree system.
Initially this is OK.
The axial pretension of the stacked battery of rubber seals & felt is however very low. By pushing the plunger down one creates a vacuum which - in combination with the friction of the seal on the rod - is pulling the rubber seal arround the rod gradually towards the vacuum chamber. This phenomenon is strongly reinforced when the initial silicone grease is gone & the rod/ seal is not greased properly.
In the end this results in the fact that one gets leakage - not over the rod sealing lip - but over the external diameter of the seal.
I proved this on a teststand whereby I installed a small 20 mm stroke pneumatic piston connected with the plunger rod & simulated a repetitive filling stroke for 2 hours at a rate of 1 stroke per second. This impleis 7200 filling strokes.
I could clearly see that the seals were somewhat "extruded " towards the vacuum chamber, resulting in leakage over their outside diameter. Note I've seen this phenomenon also on rubber seals of the worn original sealing units.
I agree this is an excessive test, and I did not test when the leakage started, but it surely revealed a trend to me.
3- Drill out the old packing unit & install an O ring fitting tight both arround the rod & the in the packingseat (O ring locked axially in place with glued locking ring)
This"Vintagepen" approach is in my opinion the most technical sound solution. I tested this method on 2 pens & obtained excellent results. Only drawback is it misses future maintenance freindliness for replacing piston seals & plunger rod seals.
The fountainbel cartrigde design overcomes all above mentioned drawbacks :
2 - O ring seals are axially pressed together obtaining a positive sealing effect both on the rod (dynamic) & in the cartridge seat (static). A separate O ring seal is provided positively sealing the cartridge outer diameter in the V1 barrel/ V2 ink container. This was deemed neccesary to avoid the need for a press fit assembly (risky for barrel cracking!) & to cope with experienced bore tolerance differences between pens.
3 -No drilling operation neccesary, nothing glued in place, easy installation from the blind cap side, replacement of worn piston seal & plunger rod seals within minutes.
Regards, Francis