Tappet Plates.

[Dan Robinson]

Somewhat relieved to discover this afternoon that the sudden and total failure of my ICS L85 was down to the tappet plate snapping. 

I called @ak2m4who graciously spoke to me out of hours,  and had an enlightening conversation and Google session.   I ordered the last one that firesupport had in stock,  which will hopefully arrive Saturday in time for Big Skirm (somehow I doubt it though).  I also found an STL file and ordered some spare scin Nylon 12.

So, the big question.... what kind of plastic is typically used on these oem parts and will Nylon 12 be stronger? 

Also,  does anyone  know of a way of cnc'ing one or of aluminium from said STL for? 

Finally,  on this topic at least,  it's there a better plastic than Nylon 12 that is regularly used in 3D printing for this type of application? 

As always,  tah in advance! 

P.S.

It was a scary moment taking that gearbox apart,  but was pleasantly surprised to see how tidy it was in there,  ignoring the bits of broken tappet plate.   A good amount of decent quality grease,  and a good air seal was found. 

 

[ak2m4]

Great chatting to you, glad you got the gearbox apart. 

 

[Sewdhull]

Somewhat relieved to discover this afternoon that the sudden and total failure of my ICS L85 was down to the tappet plate snapping. 

I called @ak2m4who graciously spoke to me out of hours,  and had an enlightening conversation and Google session.   I ordered the last one that firesupport had in stock,  which will hopefully arrive Saturday in time for Big Skirm (somehow I doubt it though).  I also found an STL file and ordered some spare scin Nylon 12.

So, the big question.... what kind of plastic is typically used on these oem parts and will Nylon 12 be stronger? 

Also,  does anyone  know of a way of cnc'ing one or of aluminium from said STL for? 

Finally,  on this topic at least,  it's there a better plastic than Nylon 12 that is regularly used in 3D printing for this type of application? 

As always,  tah in advance! 

P.S.

It was a scary moment taking that gearbox apart,  but was pleasantly surprised to see how tidy it was in there,  ignoring the bits of broken tappet plate.   A good amount of decent quality grease,  and a good air seal was found. 

Its hard to get 3d printed things like this to retain the strength of the material you are using without adding more material to the design by way of fillets or larger cross section.

Nylons are great materials but you cant clone an injection moulded design by 3d printing it and retain the strength and there's no real affordable alternative. PC and ASA again are great materials but a tappet plate gets lots of shock loading that PC would normally take, but the design of the tappet plate, I think would leave it too weak.

So short answer Nylon 6 or 12 are your best reasonable cost materials but altering the tappet plate details would get you more, eg a curve instead of a right angle at the nozzle end ( entirely dependant on the clearances you have in that area and the travel of your nozzle) and the same at the fin. Also print orientation and slicer settings to get the filament direction to follow the stresses.

Reducing the clearances ( Print it a little fatter )so the plate is better supported and so twists and flexes less is likely to help.

Gcode is CNC language and I think some where like PCB way could use that to CNC you something, or print it in a better material for you.

 

[Sewdhull]

It seems CNC from a block of POM is considered best from retro arms. Aluminium was rejected for unknown reasons.

https://www.retroarms.com/news/tappet-plates-and-how-they-are-different

 

[ak2m4]

It seems CNC from a block of POM is considered best from retro arms. Aluminium was rejected for unknown reasons.

https://www.retroarms.com/news/tappet-plates-and-how-they-are-different

POM material super nice for tappet plates and only slightly more expensive if using a mold

 

[Dan Robinson]

Intersting read that - teh Nylon plates I ordered I did wonder how they would react to continual flexing, btu ddidn't really think about impact damage.  

The printing method is supposed to be >80% solid, so hopefully that gives a little more meat to the fragile bit that broke (where the triangular part is that catches the gears).

The plates they have on Retroarms don't appeat to be ICS compatible - unless anyone knows differently?

I don't mind paying for a part that is not likely to fail; and $24 dollars seems reasonable...  Wonder if they'll make some to order?

 

[Sewdhull]

so that fin gets bent up a bit on each rotation, esp if you have play there, so it work hardens on the lower area I guess then snaps.

 

[Lozart]

so that fin gets bent up a bit on each rotation, esp if you have play there, so it work hardens on the lower area I guess then snaps.

Exactly what I was thinking.

 

[Dan Robinson]

I've sent an email to Retroarms so we will see what happens - Firesupport have dispatched my order already so fingers crossed Royal Mail are efficient and deliver tomorrow - then I shall have time to fit it to my pew fo Sunday's Big Skirm.

 

[Dan Robinson]

Just for reference,  here's the inside of the gearbox...

View attachment 133940

 

[Dan Robinson]

Well, new plate fitted (oem) and we appear to be back up and running at 1.26 joules.

Have a company looking to produce me some POM ones because I'm pretty sure it's me running g 11.1v batteries increasing the ROF that's caused it.  The gun never seems happy on 7.4s.

Retro Arms aren't doing their ones.  Will see how thr stl file I got works with the on replacement, then tak it from there.....anyone Interested in a POM on?   I assume price per unit goes down with more made.

 

[Dan Robinson]

Ooff just had the quote back for POM units...£62 each plus VAT.  Same again for the nozzle to match.  If i order five units it dropped to £55+ per unit.

Any ICS L85 owners interested? ?‍?️

 

[gavinkempsell]

Any ICS L85 owners just interested?

Not at the moment but I tend to run my ICS L85 at most game days.

 

[Dan Robinson]

Well the Nylon 12 plates have arrived and I have to say I am not overly confident in how long they will last.   I'm guessing the return spring hook will be the first to break.

Not sure I can justify £60+ for the the POM version though.  WIll have to stock up on genuine ones.

Now to find out what sized O-rings I need for the nozzle and piston.