Information here reflects things I have learned since making the build videos...
If you choose to use the same type of cylinder I did, but with cushions and and a 10 inch stroke... The cylinder would be a Parker 2x10. Model number is 2.00CC4MA1U18ACX10.00. You should go to Parker's website to find a local distributor. The distributor I found is in Richmond, VA. AFP Industries Inc. (804) 275-1436. Cost is about $213 plus shipping. If you choose to stay with an 8" stroke to minimize your air requirements, just change the 10.00 to 8.00.
When I built the original Cricket, I was very conservative when protecting the piston in the cylinder from hitting the end caps. Measuring today, it became apparent I gave up over 2 inches of the stroke to do that. It's certainly not necessary to give up that much. A quarter of an inch is more than plenty on each end. This means my tower should have been another two inches tall to maximize my full stroke. This would have given me more range for moving the stroke as well as a longer down stroke when using the single-hit feature. If you buy a cylinder with cushions, you don't need to worry about hitting the end cap on top, so make the tower tall enough to take advantage of the full upstroke. With your normal dies, the cushion on the bottom should be disabled and the dies should hit about a quarter of an inch before the piston would hit the end cap. The cushion on the bottom doesn't need to be used unless you remove the bottom die for special forging... or put on a die or bottom swage shorter than your normal die. If you are replicating the exact size of the original Cricket... and have already bought a 36" tower, I recommend that you raise the tower from the base about three inches so you can set up to get the maximum stroke. If you haven't bought your tower yet.... buy one long enough to accommodate this discussion. If you end up with a cylinder that doesn't have a cushion for the upstroke, be sure whatever you put on the tower to absorb the upstroke hit does not compress enough to allow the piston to hit the end cap.
One more suggestion this afternoon... On the original Cricket, I bolt the hand rail on the top of the tower with two bolts. They go through the hand rail into the top of the tower. Experience has enlightened me that it would be better to fabricate the hand rail so 2 bolts can be used horizontally through the tower to hold this in place. This will prevent the bolts from working loose from using the hand rail (or hitting the felt, if you are using that for an upper cushion). Note: This will add to the length requirement for the tower...
This is a long post. It address questions I have started getting questions
concerning National Standards.
When I made the videos and wrote the documentation for the Cricket, I was focused on using American standards.
I have since realized that I have started an International activity and I need to address some issues more throughly than I have.… I’m probably not going to be able to address every International issue that comes up, but a discussion about Metric vs Imperial measurements and the difference between Pipe Thread Standards commonly used in different countries can be discussed.
I’ll add (what should be) a more thorough section to the Cricket documentation on my website that will reflect the following…
Imperial VS Metric Measurements…
The Cricket (even if you decide to try to duplicate how the original Cricket was built) doesn’t need to be built with the exact sized components I reference in the videos and/or documents. Use what is available in your area, using the measurement system you are familiar with. There is no magic formula for sizing components. For example, I used 1.75 inch square bar for the tower. If what is available to you is sized using metric measurement, just use something close, just so it’s not significantly smaller. For example, use 45 or 50MM stock for the Tower (or even a bit heavier). The same applies to the angle iron and small pieces of plate to make bracketing (use 10MM for 3/8"), as well as the bolts used to hold things together. Obviously, the table and muffler can be made using thinner materials.
Pipe Thread Standards
This area is a bit more tricky… In the Air Circuit sections of the videos and the website, I refer to NPT fittings. I specified using NPT fittings and cautioned when buying fitting to be sure you get NPT.
Again…. There is no magic in the standard for the pipe fittings used on the Cricket air hammer. The key is to have consistency in what you are putting together. If you buy air valves with NPT fittings, then the fittings (nipples, elbows, hose barbs, etc) you buy to use with them should (or would best) be NPT fittings.
I don’t know about standards across the entire world (and apparently folks are already gathering material to build Crickets in many countries already), but I am aware that in some places only the British Standard Pipe fittings are readily available.
NPT and BSP fittings have the same threads per inch, but the pitch the threads are cut are different (60 VS 55 degrees).
The fittings can be mixed (they will screw together), but will leak if just screwed together. I have read they can be mixed if a good sealant is used (I have not tested this).
The best case would be to have the entire air circuit use the same standard. If that’s not possible, at least use a professional level sealant. I will order a couple BSP fixtures and test to verify if the standards can be mixed and still seal.
I would recommend using sealant, as opposed to teflon tape. Teflon tape is fine if you just tighten and not back off. If you use tape, then back off (for alignment reasons), the joint will likely leak, even if the fittings are of the same standard. Sealant is less (or not) likely to leak if you back off (my experience). There is a wide variance in sealant quality. I use LockTite 565.
The original Cricket (as documented in the videos) has milled-in slots for gibs in the Ram Assembly. During the video, I recommend an alternate method that does not require the use of a mill. Although I mentioned the alternate method, I didn't provide much detail. I have added a 13th video showing all the parts and assembly construction for the new method. It's easier and better than milling the slots. It allows for full width gibs.
There has been some interest in specifics for Jimminy....
It weighs 160# (not including the stump)
Base: 8 x 11 x 1.5"
Anvil: 2.5 in Sq, 15" long
Tower: 1 3/8 sq cold rolled, 28.5" long
Dies: 1 x 2.5", 1" tall
Table: 1/2" plate
Ram: Same stock as Anvil 3.5” long
Guidance System: All 3/8” angle iron
Gibs: 3/8 HDPE with 1/4 steel plate backing plates
4-Way Valve: MettleAir: 4A410-15
Cylinder: Hydro-Line 1.5 x 5 (mounts directly to the table)
Check Valve: Less expensive (still bronze body)
All else: Same as Cricket… However…
No Air Gate…. However…
I am just experimenting with the less-expensive 4-Way valve (I don't know about durability yet). This is a Chinese valve... so far it's holding up.
MettleAir has a website.
I will be adding a Humphrey 31P as an Air Gate. I don't know yet if the MettleAir 4-Way valve will support the Air Gate the same way as the Norgren(spool management issue).
The MettleAir valve supports the single-hit and clamp just fine.
The Humphrey 31P valve works well as the Air Gate.
I'm going to replace the Roller Valve with a smaller (less expensive) Norgren roller valve (03041122). I expect it to work. (It did work)
I built the frame, all assemblies and (frame) brackets the same as the Cricket using materials I already had in my shop (which again, is why the components of this hammer are these dimensions).
Obviously, the bracketing for the air circuit is different.
If some of you want to make an even more-simple hammer, you can eliminate the Air Gate (you lose single-hit and clamp features) and the Stroke Adjustment Assembly (you would have a single stroke position). Also, if you don't mind having the roller valve above the table, you could eliminate the Ramp-Dock Assembly (you still have to put something above the table to mount the roller valve). You could probably build the whole hammer in about 3 days (after you have the goods). If you are going to make a smaller version, you wouldn't need stroke adjustment anyway....