HPR spiral fillers...

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

ewomack

Well-Known Member
TRF Supporter
Joined
Jul 8, 2019
Messages
911
Reaction score
830
I used the filler below for filling spirals on LPR kits, but would it stand up to HPR?
If not, any suggestions for filling spirals on a 4" Super DX3?

IMG_3705.JPG
 
I've used that for a few mid power rockets and I've also troweled it into balsa and basswood surfaces (scraping it down of course) and it works pretty well for wood surfaces and spirals. I expect lots of folks have used it successfully for HPR. I find bondo spot putty sticks a lot better, and structurally somewhat stronger, but should be used under good ventilation... or a respirator (don't think I use my respirator EVERY time...big jobs i try to do outdoors). But bondo works amazingly well, and spirals on my aerotech astrobee d and Cherkee G for example, are totally invisible. If the joint is under stress, however, such as a tube joint, a hairline crack can form from the flex. Making sure you have it glued together well helps of course. For high power, bondo would be my choice... although I'll be watching for bettr ideas!
 
Last edited:
I find bondo spot putty sticks a lot better, and structurally somewhat stronger, but should be used under good ventilation... or a respirator (don't think I use my respirator EVERY time..
Bondo only has one warning label on the back " causes eye irritation", not may cause, but causes and man does it ever, it felt like somebody threw a handful of sand in my eyes for three to four days the first time I used it......and most of the body fillers are the same way.
 
Bondo only has one warning label on the back " causes eye irritation", not may cause, but causes and man does it ever, it felt like somebody threw a handful of sand in my eyes for three to four days the first time I used it......and most of the body fillers are the same way.
That may be ... I've never had that issue, but I feel it in my chest when I work with it too much indoors w/o my respirator! The smell is reminiscent of toluene... whatever it is, I feel like it can't be good for you :)
 
That may be ... I've never had that issue, but I feel it in my chest when I work with it too much indoors! The smell is reminiscent of toluene... whatever it is, I feel like it can't be good for you :)
I ended up having to get a full face, clear mask that has respirator cartridges on each side.
 
That may be ... I've never had that issue, but I feel it in my chest when I work with it too much indoors w/o my respirator! The smell is reminiscent of toluene... whatever it is, I feel like it can't be good for you :)
Look up the MSDS on Bondo spot putty, way more than an eye irritant,
contains benzenes and ketones which are known carcinogens.
 
Bondo only has one warning label on the back " causes eye irritation", not may cause, but causes and man does it ever, it felt like somebody threw a handful of sand in my eyes for three to four days the first time I used it......and most of the body fillers are the same way.

Wow, first time? I figured you'd used it before.

I like the smell of most of those things. Particularly polyester resin- Bondo body filler or fiberglass resin. There's something about spreading a little Bondo and cutting it down with a cheese grater that's just satisfying.

I'll second the glazing/spot putty for filling an imperfections on a tube. It dries fast and sands well. That said, if I had CWF like @ewomack does and no glazing putty, I'd use what I had on hand.
 
I use and Highly recommend GoodFila CWF. Creamy smooth, easy to sand, dries fast. I cover the whole tube. I put on nitrile gloves scoop some up and rub it up and down the BT. Let it dry a couple of hours and sand it off. I start with 120, then 220 then 400. You can thin it easily. You can paint it on small blemishes. I use it on balsa and plywood. I used to use Elmer's CWF. Not anymore. No Bondo either. Too toxic.
 
I use and Highly recommend GoodFila CWF. Creamy smooth, easy to sand, dries fast. I cover the whole tube. I put on nitrile gloves scoop some up and rub it up and down the BT. Let it dry a couple of hours and sand it off. I start with 120, then 220 then 400. You can thin it easily. You can paint it on small blemishes. I use it on balsa and plywood. I used to use Elmer's CWF. Not anymore. No Bondo either. Too toxic.
I've not heard of that brand before.
 
Look up the MSDS on Bondo spot putty, way more than an eye irritant,
contains benzenes and ketones which are known carcinogens.
The SDS I found for3M's Bondo spot putty shows styrene monomer and polyester resin as the major organic products. Benzene isn't listed, nor are any ketones I'm familiar with. Toluene, less than 0.15%. Products that contain significant amounts of benzene are generally hard to find---and expensive, what with shipping and regulations that follow a carcinogen.

The SDS appears to have several Bondo products listed and they're a bit mixed up, but the information above is for the spot putty specifically.

[FWIW there is no such thing as "benzenes". Benzene is a specific compound, C6H6. Lots of compounds contain its structure---including three of the amino acids that are in your body's proteins---but that doesn't make them benzene, nor does it make them carcinogens.]


EDIT: My bad, 3M's SDS online is definitely and badly mixed up. The tube of spot putty I have lists some the ingredients and they're quite different from the SDS list. Spot putty does contain acetone and methyl isobutyl ketone, as well as ethylbenzene and xylene. The latter two have a benzene ring in the molecule but as I mentioned above, that doesn't make them benzene. Neither is classified as a carcinogen, except possibly in California...
 
Last edited:
The SDS I found for3M's Bondo spot putty shows styrene monomer and polyester resin as the major organic products. Benzene isn't listed, nor are any ketones I'm familiar with. Toluene, less than 0.15%. Products that contain significant amounts of benzene are generally hard to find---and expensive, what with shipping and regulations that follow a carcinogen.

The SDS appears to have several Bondo products listed and they're a bit mixed up, but the information above is for the spot putty specifically.

[FWIW there is no such thing as "benzenes". Benzene is a specific compound, C6H6. Lots of compounds contain its structure---including three of the amino acids that are in your body's proteins---but that doesn't make them benzene, nor does it make them carcinogens.]


EDIT: My bad, 3M's SDS online is definitely and badly mixed up. The tube of spot putty I have lists some the ingredients and they're quite different from the SDS list. Spot putty does contain acetone and methyl isobutyl ketone, as well as ethylbenzene and xylene. The latter two have a benzene ring in the molecule but as I mentioned above, that doesn't make them benzene. Neither is classified as a carcinogen, except possibly in California...
The 3m SDS clearly states that the product is a category 2 carcinogen, and specifically lists Ethylbenzene and Methyl Isobutyl ketone as carcinogens
 
I use and Highly recommend GoodFila CWF. Creamy smooth, easy to sand, dries fast. I cover the whole tube. I put on nitrile gloves scoop some up and rub it up and down the BT. Let it dry a couple of hours and sand it off. I start with 120, then 220 then 400. You can thin it easily. You can paint it on small blemishes. I use it on balsa and plywood. I used to use Elmer's CWF. Not anymore. No Bondo either. Too toxic.
these are the ones on their website:
 
Years ago, a neighbor recommended a 2-part glazing putty to make my fiberglass work look better. As I recall, it was a bit pricy, but was great to work with and sanded well. The container was similar to Evercoat 482, and I feel like it was an Evercoat product, but apparently that style of container is used by multiple companies. I recall the mixed color to be a light green.

Sandy.
 
The 3m SDS clearly states that the product is a category 2 carcinogen, and specifically lists Ethylbenzene and Methyl Isobutyl ketone as carcinogens
From epa.gov: "EPA has classified methyl isobutyl ketone as a Group D, not classifiable as to human carcinogenicity." NIH says that ethylbenzene is a potential carcinogen, demonstrated to a limited extent in lab animals but not yet in humans. Considering how ubiquitous "potential carcinogens" seem to be...
 
From epa.gov: "EPA has classified methyl isobutyl ketone as a Group D, not classifiable as to human carcinogenicity." NIH says that ethylbenzene is a potential carcinogen, demonstrated to a limited extent in lab animals but not yet in humans. Considering how ubiquitous "potential carcinogens" seem to be...

Terry and I are just getting chemistry-nerdy here...

Benzene is a carcinogen because it intercalates into DNA. (It slides between the "rungs" of the DNA "ladder" and fouls up the replication process.). Surprisingly, the 2-carbon ethyl group on ethylbenzene, and even the one additional carbon on toluene, prevent intercalation, so they are not near as carcinogenic.
 
An interesting alternative to Bondo is a filler called Super-Fil. It is an epoxy based lightweight two part filler. Very low on odor and sands like a dream. When I use Bondo (or any polyester based material) I put a fan next to me blowing away and try to work outdoors. The solvents in it, if you don't do something to avoid breathing the fumes, result in you being able to hear your brain cells swelling up and popping.

https://www.aircraftspruce.com/catalog/cmpages/superfil.php
 
I used the filler below for filling spirals on LPR kits, but would it stand up to HPR?
If not, any suggestions for filling spirals on a 4" Super DX3?

View attachment 541502
Just go fiberglass; just kidding. It should work but Bondo spot filler like other folks have said is much faster; just use it outside because it has very strong fumes. I do a little at a time because it dries fast.
 
Just go fiberglass; just kidding. It should work but Bondo spot filler like other folks have said is much faster; just use it outside because it has very strong fumes. I do a little at a time because it dries fast.
The only warning on the back of the Bondo Spot Putty says: "Causes Eye Irritation" It does too. My eyes feel like someone threw sand in them unless I wear a full face respirator.
 
The only warning on the back of the Bondo Spot Putty says: "Causes Eye Irritation" It does too. My eyes feel like someone threw sand in them unless I wear a full face respirator.
I use a respirator, gloves, and other PPE for all of my high power building. We use very strong chemicals unless you only use Titebond on your builds. I have went too far down the fiberglass rabbit hole to not use proper PPE. Plus I'm also usually doing builds with my kids so they PPE up too.
 
Wow, first time? I figured you'd used it before.

I like the smell of most of those things. Particularly polyester resin- Bondo body filler or fiberglass resin. There's something about spreading a little Bondo and cutting it down with a cheese grater that's just satisfying.

I'll second the glazing/spot putty for filling an imperfections on a tube. It dries fast and sands well. That said, if I had CWF like @ewomack does and no glazing putty, I'd use what I had on hand.
Make sure WHICH Bondo Glazing and Spot Putty you have, there are two versions both red, one is a single part and is basically a very high solids lacquer filler (lots of solvents), the other is a two part filler that iirc is polyester based and uses a salicylic acid based hardner (it has similar reactions if the user is susceptible to epoxies, which it basically is). The two part is Bondo Professional Glazing and Spot Putty the single part is Bondo Glazing and Spot Putty.
 
Make sure WHICH Bondo Glazing and Spot Putty you have, there are two versions both red, one is a single part and is basically a very high solids lacquer filler (lots of solvents), the other is a two part filler that iirc is polyester based and uses a salicylic acid based hardner (it has similar reactions if the user is susceptible to epoxies, which it basically is). The two part is Bondo Professional Glazing and Spot Putty the single part is Bondo Glazing and Spot Putty.
I may, or may not, have "a problem". Bondo Glazing & Spot Putty in the foreground. Not pictured is anything I consider as an adhesive including way too many different epoxies including one of the two part moldable epoxies which I used for fillets on my first HPR rig...never again. I also tried it on tube spirals on a different rocket and...never again.

I generally (tho limited experience) use the Bondo spot putty on HPR (I'm also weird like @tsmith1315 in that I seem to like the smell). It's pretty good for spirals. It does dry incredibly quickly, like annoyingly quickly sometimes. I used to try and use a putty knife to smear it in and level it, but it dries so fast that I would often just pull some out, so I usually devolve into squeezing it out directly into the spirals and/or smearing it in using my gloved fingers. I use it to feather wonky transitions and clean up fillets as well. With fillets, I smear it in with a finger and quickly wipe off any excess so there isn't much to sand.

On LPR spirals (if I address them at all) and on balsa fin grains, I use one of the pictured wood fillers, diluted with water and painted on. If the spirals are deep I just use my finger and less water. If the balsa seems weak, or I don't want to deal with all this (which is pretty common now), then I will paper the fins. I have also been known to put on a coat or two of wood hardener (tho it's kinda nasty), usually one before and then after the wood filler or just after, or whenever I remember ;)

Because of this thread tho, I've already bought some of @teepot's GoodFilla and I'm strongly considering ordering some of @H_Rocket's Super-Fil as I do worry that the Bondo spot & glazing is going to show cracks at some point if the part (body tube especially) flexes too much or too often. That, and I'm always on the lookout for better shaping & filling with less sanding.
 

Attachments

  • PXL_20221213_043740452.jpg
    PXL_20221213_043740452.jpg
    2.2 MB · Views: 0
Back
Top