A Dashpot was not a Dashpot is a Dashpot

[Soulbear]

Hi Trolls,
In the course of my Lazarus Lathe Project, I used an "Airpot Dashpot" that I had "Earmarked" for another project, and so I needed to replace it. Now getting a little "Fed Up" with being "Shafted" with extortionately high charges by U.K. suppliers, for these (In U.K. terms) relatively difficult to source items, (The Airpot cost me around £70+Tax here in the U.K.) I started having a look around on the ubiquitous Bay and located a much more realistically priced replacement, this one :-

Airpot Dashpot.jpg

Airpot Dashpot1.jpg

Airpot Dashpot2.jpg

The vendor described it as a Dashpot, N.O.S. complete with original packaging and instruction sheet. All this, and for only $25, and even with postage costing around another $20+ it still came in at around £40, much less than half the cost from my U.K. based supplier. I promptly hit the payment button, and eagerly awaited delivery of my "Bargain Buy" from the good ol' U.S.of A. However, when it arrived, all was not as it had first appeared. Soulbear
Continued........

[Soulbear]

Hi Trolls,
When the "Dashpot" arrived from the U.S. I only gave it a cursory looking over, by checking that it had not been damaged in transit, and being somewhat pre-occupied with my Lazarus Lathe Project, I set it to one side. Today, having a moment or two to spare, I took a "Closer Look" at the Dashpot and was somewhat "Slightly Peeved" to find that the Piston appeared to only offer "Resistance" or Damping" in one direction only, when sliding within the Glass Cylinder. I thought at first that I must have been sold a "Lemon" and took a closer look at the Airpot. I completely removed the "Cone Shaped" Damping Adjustment Screw and could see that it appeared to be in "First Class" Condition. I then took a look at the "Airpot" website and whilst having a "Good Nosey" around the site, I came across this :- "When controlled deceleration is required at the end of the stroke of your mechanism, the Airpot "Snubber" configuration is particularly useful. It performs push damping only" So now the 1-Way Damping began to make sense. My Dashpot is not a Dashpot, but a Snubber!! I then removed the Graphite Piston from the Cylinder and noted that there appeared to be the Tiniest of "Ports" at the top of the Piston. Within the Piston I suspect there is some form of "Schrader" Type Valve as used in Pneumatic Tyres, and this would account for the 1-Way Damping. Now Trolls, £40 is still £40, and I'd paid this out because I wanted a replacement Dashpot not a Snubber, so I got on with trying to disable this Valve. My first attempt "Failed" because to disable the the Valve I simply mixed up some "JB Weld Epoxy" and coated the Top of the Piston. It worked insofar as I now had "Damping" on both strokes of the Piston, however. there was some "Free Travel" on the "Connecting Rod" on the underside of the Piston in 1 direction of travel. This I think was caused by the "Schrader Valve Spring" compressing slightly. I scraped off the JB Weld Epoxy from the Graphite Piston, before it had "Fully Cured" to see what else I might do. Now Trolls, I've broken quite a number of small and ultra small drill bits over the past few days and weeks, and for whatever reason I've not thrown them all away, I'd put some of the broken drill shanks in a pin tray. One of these drill shanks was a "Perfect Fit" within the Piston "Port" so it was pressed in with a dab of Epoxy on it, thereby compressing the Schrader Valve Spring and eliminating the Connecting Rod's "Free Travel" It was then ground down "Flush" to the Top of the Cylinder. I've now covered it, and re-covered the Piston Crown with Epoxy, and now things are A OK. Providing the "Dashpot is propperly adjusted once fitted, to ensure the Piston Crown cannot come into contact or foul the end of the Cylinder, I should have the Dashpot I thought I'd initially bought :-

Airpot Snubber Modification1.jpg

Airpot Snubber Modification3.jpg

Airpot Snubber Modification2.jpg

So you see Trolls, my Dashpot, which wasn't a Dashpot, is now a Dashpot!! Te He!!
Regards Soulbear