B219 FEL Improvement

[Lil Foot]

After rebuilding my B219 FEL, a little forensic work on the old wiper seals & o-rings revealed that most of the damage was from grit- Arizona is dusty, dusty, dusty. I felt that if I could keep most of the dirt from reaching the seals, their life should be extended noticeably.
I found that clamp-on rubber caps for 2" ABS were exactly the right ID for the OD of my cylinders. I cut a 1 1/8" hole in the cap, & slit it so I could get it around the ram & cylinder. I had some 3" X 3/16" industrial felt laying around, so I made (8) 2 3/16" OD felt washers with 1 1/8" holes, & slit them also. A few drops of oil on each washer, assembled them so none of the slits lined up, and clamped them in place. They clear everything on the FEL all through it's travel, and should cut down the dirt intake- easy to remove & clean if necessary.
Caps were $2.90 each.

 

[Lil Foot]

Finished product installed:

 

[Lil Foot]

And a Big Thanks to BadDog, your measurements were right on, and saved me a 270 mile round trip to take my own measurements.

 

[OldeEnglish]

Thats really slick Lil Foot! I bet that will be a big help keeping the dust out.

 

[kubotasam]

How did you cut such perfect circles?

 

[Tooljunkie]

Nice. I agree it will help keep grit out. But it will need to be serviced often. To prevent it from turning into something like scotchbrite. Having a spare set of felts to wash/dry and lube for next swap would be good.

 

[Lil Foot]

How did you cut such perfect circles?

To cut the hole in the cap, I made a 1 1/8" punch from scrap steel, and a black plastic centering "doughnut" that was a slip fit for the ID of the cap & the OD of the punch. (1st pic) Light pressure in the press with a piece of rubber gasket material for backing. Normally this would have worked perfectly, but there was a complication- the end of the cap is concave (dished) about 3/16", and is THICK, about 5/16". This allowed the cap to flex outward as it was punched, and when it sprang back, the hole was tapered & undersized. I grabbed a piece of scrap plastic from the stash & made a fixture to hold the cap in the lathe, and cleaned up the hole with a SHARP boring bar. (2nd pic) The slit in the cap was done with a very fine modeler's saw.
To cut the felt, I used the punch by hand with a twisting motion against rubber backing to cut the center hole. Then I traced the outside diameter with a felt tip using the "doughnut" as a template, and cut it by hand with scissors.
P.S.- I know not everyone has access to a lathe & such, but I figure most people are imaginative & will come up with other methods if necessary. For example, I considered trying to melt the hole through the cap as a fall back method if the punch & such failed.

 

[Lil Foot]

Nice. I agree it will help keep grit out. But it will need to be serviced often. To prevent it from turning into something like scotchbrite. Having a spare set of felts to wash/dry and lube for next swap would be good.

Thanks, probably won't need to be cleaned as often as you might think. I am probably opening a counter-intuitive can o' worms here, but as a research technician with extensive grinding & polishing experience, I can predict that the felt & dust will tend to finely polish the rams, if they have any noticeable effect at all.

When grit is between two hard surfaces, it cuts deeply into both surfaces- the softer of the two more deeply. Virtually all grinding is an example of this. However, virtually all polishing is done between a hard surface (the workpiece) and a soft media carrying the grit. Greatly simplified, this soft media allows the piece of grit to "sink in" into the media, leaving only the tiniest fraction of the grit exposed, and with very little cutting pressure to engage the workpiece. Virtually all optics & such are polished using a soft medium. (felt, other cloths, wood, mixtures of beeswax, tree rosin, (sap) even rubber compounds, etc.)
(I can show pics of some soft polishing plates from my home setup if anyone is interested)

But what about scotchbrite & sandpaper, you might ask? On the surface they don't seem hard, but their abrasives are held rigidly in bonding media, with only the backing being flexible.

Of course, all of this assumes I won't allow the dirt to build to the point that the felt & caps become packed so solidly that they become a rigid holder for the grit, and begin grinding the rams. Then your concern would be well justified, and I would deserve to have to buy new cylinders.
My seat of the pants guess is cleaning once a season, based on my very part-time use of the tractor, (it's 150 miles from me 90% of the time) but I'll have to play it by ear. I have a good supply of felt, so I'll probably make another set of felts as per your suggestion. Thanks.

 

[barts]

On motorcycles, rubber boots are used to keep rocks, etc. from dinging the tubes... fork boots handle ~13 inches of travel; w/ a bit of plastic up they could be doubled up.

The industrial felt is the approach I used when I made way protectors for my lathe - keeps metal/grit from getting under the carriage on my metal lathe.

- Bart

 

[BadDog]

And a Big Thanks to BadDog, your measurements were right on, and saved me a 270 mile round trip to take my own measurements.

Happy to help, and glad it worked out for you.