first grain glue job

[watermelonman]

I am about to embark on building my first motor with glued grains. I was going to pick up the recommended Gorilla glue for the job. Any specific issues to watch out for? I am a little nervous about pot time and making sure it is all sitting in the liner properly.

 

[cvanc]

Dry fit EVERYTHING before you begin! And stop and resolve all fit problems BEFORE you open the glue.

1) Liner into casing
2) Grains into liner
3) Sort grains by tightness of fit into liner (loosest to tightest) - install loose ones first as they have a long way to travel, finish with tightest ones
4) After you glue your grains into the liner, set (assembled) liner aside and let glue dry completely BEFORE you load it into your casing
5) Use a razor blade to clean any dried glue off the outside of your liner assembly before you install it into the casing
6) Coat casing and/or liner with spray silicone for easy assembly and cleanup
7) Load liner assembly into casing and attach end closures as usual

...That's how I do 75 and 98 loads. I learned this sequence painfully, after some expensive mistakes. It works for me. Good luck!

 

[watermelonman]

That is encouraging and helpful. Thanks much!

 

[ChrisAttebery]

That's an excellent list. Noted for future use.

 

[jd2cylman]

Dry fit EVERYTHING before you begin! And stop and resolve all fit problems BEFORE you open the glue.

1) Liner into casing
2) Grains into liner
3) Sort grains by tightness of fit into liner (loosest to tightest) - install loose ones first as they have a long way to travel, finish with tightest ones
4) After you glue your grains into the liner, set (assembled) liner aside and let glue dry completely BEFORE you load it into your casing
5) Use a razor blade to clean any dried glue off the outside of your liner assembly before you install it into the casing
6) Coat casing and/or liner with spray silicone for easy assembly and cleanup
7) Load liner assembly into casing and attach end closures as usual

...That's how I do 75 and 98 loads. I learned this sequence painfully, after some expensive mistakes. It works for me. Good luck!

Sticky!

 

[markkoelsch]

There is one thing possibly not mentioned in Carl's list. In some motors, I do believe the grains need to be inserted in a certain order. This is the case with certain Loki loads that utilize a stepped or tapered core if memory serves.

 

[JimJarvis50]

If you have spacers also, then you might find my approach helpful.

Jim

https://www.rocketryforum.com/showthread.php?133825-CTI-Space(r)-Race

 

[cvanc]

There is one thing possibly not mentioned in Carl's list.

Oh, there's a lot of things not mentioned in my list - like the motor vendors' complete instruction sheet! (Which needs to be followed, of course.) These are just the steps I've added along the way.

The issue of stuff not fitting right and binding WILL intrude sooner or later. It's best to head it off and not discover it by surprise when half the grains are in and the glue is setting faster than you ever remember it setting before and there's sweat dripping into your eyes 'cuz it's ninety two degrees in the garage and your glasses just tried to slip off your face and you pushed them back on instinctively not remembering for a moment how much damn glue was on your fingers and this is about the time they can hear you swearing from inside the house :rofl:

 

[gerbs4me]

At what size motor do you start having to glue the grains?

 

[tim cubbedge]

At what size motor do you start having to glue the grains?

It varies. Some Loki 38mm & 54mm require it. Some CTI 75mm require it. Not sure about AT or others.

 

[gerbs4me]

It varies. Some Loki 38mm & 54mm require it. Some CTI 75mm require it. Not sure about AT or others.

Thanks!

 

[Steve Shannon]

Most motors (even 75s and 98s) don't require gluing. Just read the instructions in advance.


[emoji1010] Steve Shannon [emoji1010]