Need some threaded caps 3D printed

[YYCHM]

I'm using a standard lever action grease gun to oil my mill and as such don't have use for the spring and plunger found in a standard grease gun. I need to seal the top of the grease barrel to make the whole thing leak proof. I'm thinking a 3D printed threaded cap would work.

The barrel OD on the threads is 2.224", there is 1/2" of thread and they appear to be 10 TPI. The cap should be fairly beefy maybe 1/4" thick in case I need to install some sort of vacuum breaker in it. Looking for maybe 2-3 caps in order to have some spares.

Should be a pretty easy project for someone familiar with CAD/CAM and a 3D printer.

An alternative would be to print a container that looks like the grease gun tube only sealed on one end and probably much shorter.

If you're interested and willing to help, please PM me.

Thanks,

Craig

 

[Johnwa]

I’ve never been able to print workable threads. Wouldn’t the easiest solution be the original cap and a bit of jb weld?

 

[Janger]

4 hour print time Craig. I'll see if I can get it going tomorrow. That's on fairly draft setting of 15% infill. It probably won't be strong enough at that and will need to be printed again with more density and perimeters. This will be enough to test fit up. The other part is a screw in part to test the first. Also it may require chucking up in the lathe and cleaning up/chasing the thread. hmmm maybe could chase the thread on the mill.

 

[Janger]

CAD... note the thread.

 

[YYCHM]

4 hour print time Craig. I'll see if I can get it going tomorrow. That's on fairly draft setting of 15% infill. It probably won't be strong enough at that and will need to be printed again with more density and perimeters. This will be enough to test fit up. The other part is a screw in part to test the first. Also it may require chucking up in the lathe and cleaning up/chasing the thread. hmmm maybe could chase the thread on the mill.

View attachment 10720

Cool! PM sent.

 

[RobinHood]

How about 2” ABS pipe with a cap glued on? Nominal ID of that pipe is 2”. With the cap, the OD will be about 2.7”. Cut the pipe flush with the end of the cap after glue has set. Bore and thread as required to fit the grease gun. Cheap and easy to machine.

My original push Oiler uses a flexible plastic piston that goes inside the cylinder. After filling the Oiler, just push the piston on top of the oil. The air escapes during that process. Once the piston is on top of the oil, it seals the bore. As the oil is drawn out via the pump, the hydraulic pressure pulls the piston along, keeping things sealed. There is a pull chain attached to the piston to pull it out by first breaking the hydraulic lock and then retrieving it out of the cylinder. Seems to work well.

 

[YYCHM]

How about 2” ABS pipe with a cap glued on? Nominal ID of that pipe is 2”. With the cap, the OD will be about 2.7”. Cut the pipe flush with the end of the cap after glue has set. Bore and thread as required to fit the grease gun. Cheap and easy to machine.

This is worth a try all right. 2" ABS appears to be the perfect size. 2" ID and 2.375" OD. The threads on the gun tube are really shallow. It will give me a chance to try internal threading on the lathe to boot.

Thanks Rudy!!

 

[RobinHood]

You are welcome.

Yes, and it is a nice big bore so you can see what is going on while you are threading.

Plastic is also forgiving in case of a mishap; I use quite a bit of it to make prototypes and to validate proof-of-concept.

 

[YYCHM]

You are welcome.

Yes, and it is a nice big bore so you can see what is going on while you are threading.

Plastic is also forgiving in case of a mishap; I use quite a bit of it to make prototypes and to validate proof-of-concept.

What's a proper internal threading tool look like?

Thanks,

Craig

 

[Brent H]

@YYCHobbyMachinist : typically a boring bar set up wit a tool bit sharpened to 60 and set up such that the 60 is perpendicular to the work piece (same as if exterior threading)

Or a boring bar with HSS tool blank inserted

 

[YYCHM]

I have this.....

But they sure didn't attach that carbide tip on it very square.

 

[PeterT]

I don't quite understand what the cap is trying to accomplish because (I think?) its a converted grease gun? I guess it depends on the design. I thought the rod & spring was to provide enough squeeze pressure to get viscous grease into the injection chamber & that's where the high pressure piston delivers into the hose. I don't think you have high pressure in the main chamber. You are just holding it upright so the oil column is over the lever head? Why not just use the original cap & plug the rod hole?

 

[YYCHM]

I don't quite understand what the cap is trying to accomplish because (I think?) its a converted grease gun? I guess it depends on the design. I thought the rod & spring was to provide enough squeeze pressure to get viscous grease into the injection chamber & that's where the high pressure piston delivers into the hose. I don't think you have high pressure in the main chamber. You are just holding it upright so the oil column is over the lever head? Why not just use the original cap & plug the rod hole?

It's a little more complicated than just plugging the rod hole.

However this rubber piston could probably be bolted to the cap and would seal ok.... maybe. The through bolt would have to be sealed some how.

I'm sort of in the mind set to keep it in it's original configuration in case I want to relegate it back to grease duty. But considering it's a $6 item why not just sacrifice it eh.

If I could find a cap that fit the barrel snug enough, I'd be tempted to cut the barrel down a few inches and glue the cap in place. You can fill oil from the pumping end.

Craig

 

[Janger]

Quotes from online:

Just for fun I uploaded that cap to a 3D printer quote engine. Cheapest was $29 CAD including shipping. $41 for two. Printed with PLA. PETG was $32. Polycarbonate $37. Nylon $61. Then it gets interesting. $160 for castable wax! 316 Sintered Stainless Steel $362. PEEK $328. Aluminium $372. Stainless $589 (not sintered?). Bronze $966. Copper $1037. Titanium ! $1400 and finally sterling silver at $1900.

 

[YYCHM]

Quotes from online:

Just for fun I uploaded that cap to a 3D printer quote engine. Cheapest was $29 CAD including shipping. $41 for two. Printed with PLA. PETG was $32. Polycarbonate $37. Nylon $61. Then it gets interesting. $160 for castable wax! 316 Sintered Stainless Steel $362. PEEK $328. Aluminium $372. Stainless $589 (not sintered?). Bronze $966. Copper $1037. Titanium ! $1400 and finally sterling silver at $1900.

Seriously? $30 for a plastic cap?

 

[Janger]

it's all about the machine time and labor. it's interesting isn't it. I got a quote from protolab on a 3D machined aluminium part about 2.5" diameter and 1.5 inch tall. It was $200+ for one and the price rapidly fell down to about $30 or $40 each in qty of 20. An injection molded cap in quantity (thousands or more) would maybe be $1 BUT you need a $20k or $50k or 80k precision mold made first. and setup time.

How much would you want to pay for 4 hours of print time?

 

[YYCHM]

Who would have thought this would be an issue......

Ten attempts to thread this now and getting no where. The work piece keeps pulling out of the chuck mid thread pass. I've tried chucking it with both out-side and in-side jaws to no avail. Just too slick and flexible to grab properly.

I'm no longer convinced 3D printing is viable either. The threads on the barrel are not a standard profile probably to accommodate the cap threading which looks to be rolled or even stamped.

 

[Janger]

If you made a round steel plug diameter of the inside of the tube (2"?) then you could put that inside the tube to tighten the jaws against. I bet you could grip it better then.

 

[Janger]

put sandpaper between the jaws and material too.

 

[Janger]