Source of fin ply needed

[Banzai88]

Does anyone know of a "GOOD" source of 1/4" ply suitable for HP rocket fins that's actually flat and usable?

Seriously, the last 2 shipments that I've gotten from LOC and others has at least 1 out of every 3 sheets that's warped so bad you would think that it was cut from an English Longbow. I'm not even sure a human looked at them before shipping them, because no one in their right mind would send crap like that out the door.

And before you say "Just call 'em, I'm sure they'll send you replacements"....I've already done that. Twice. STILL have yet to get 3 pieces of ply that are flat. The last 'replacement' that I was sent was warped MORE than the original it was supposed to replace! And that's from 3 different 'rocketry' vendors!

Local sources of Midwest hobby ply is just as bad or worse!

 

[jbrracer]

ive had good luck at hobby lobby and menards. You could go to fiberglass.

 

[teepot]

Have you tried Balsa Machining?

 

[SDramstad]

Aircraft Spruce https://www.aircraftspruce.com/catalog/wppages/finnishbirch.php

 

[tfish]

2x Aircraft Spruce 1/4" 12 ply

Tony

 

[heada]

Local woodworking supply. Look for baltic birch or cabinet grade ply. And woodworking supply isn't lowes or home depot. Its more like Rockler or Woodcraft but those are overpriced.

 

[prfesser]

Menards has/had a kind of 1/4" underlayment, five-ply and flat enough that I made more than a few fins and centering rings from it. Pretty heavy, though. Sorry but I don't recall the name. We have a new Menards reasonably close by, and they have Baltic Birch in several thicknesses.

For Dobsonian telescopes the premier plywoods are Baltic Birch and Appleply, with Appleply being the top choice (no, it's not made from apple wood, nor is it an offshoot of Steve Jobs). A telescope mount has to be reasonably dimensionally stable, stiff, and reasonably lightweight. Appleply is all-hardwood, while many other types of plywood have hardwood veneer over softwood core layers. It's not cheap, though.

 

[heada]

Menards has/had a kind of 1/4" underlayment, five-ply and flat enough that I made more than a few fins and centering rings from it. Pretty heavy, though. Sorry but I don't recall the name. We have a new Menards reasonably close by, and they have Baltic Birch in several thicknesses.

For Dobsonian telescopes the premier plywoods are Baltic Birch and Appleply, with Appleply being the top choice (no, it's not made from apple wood, nor is it an offshoot of Steve Jobs). A telescope mount has to be reasonably dimensionally stable, stiff, and reasonably lightweight. Appleply is all-hardwood, while many other types of plywood have hardwood veneer over softwood core layers. It's not cheap, though.

For example of "appleply" I can get A grade of 4 'x 8' x 3/4" red oak plywood for $87 a sheet but if I switch to the "all hardwood core" version, same size and grade is $118

 

[RocketflierVB]

JoAnn's Fabric. That is where I get my 1/8 and 1/4 inch plywood.

 

[tim cubbedge]

Always Ready Rocketry
https://alwaysreadyrocketry.com/product-category/cnc-services/

 

[RocketScott]

Might be worth backing the bus up a bit

To the OP: Have you tried flattening the plywood? It was made flat and wants to be that way

Try leaving it on a flat surface with a little bit of weight on it. Warming it up will help, no need to bake it but a space heater blowing on it can't hurt. You can also try running an iron over it. Cover it with a dish towel (the thinner kind) to keep from scorching it

 

[RobertH3]

Sig. Glue two sheets of 3/32" 5 ply together for 3/16" 10 ply or 2 sheets of 1/8" 5 ply together for 1/4" 10 ply. I used tite-bond 2 and weights. The super ply is less susceptible to warping and strong!
My overbuilt solution...
Cheers /Robert

 

[Banzai88]

Might be worth backing the bus up a bit

To the OP: Have you tried flattening the plywood? It was made flat and wants to be that way

Try leaving it on a flat surface with a little bit of weight on it. Warming it up will help, no need to bake it but a space heater blowing on it can't hurt. You can also try running an iron over it. Cover it with a dish towel (the thinner kind) to keep from scorching it

I got 10 sheets of ply this week in 3 shipments from 3 different vendors, with 1 bad sheet in each shipment.

7 are fine, straight as arrows. Of the 3 that are warped, I steamed all 3 and clamped them. 1 has responded and looks like it's going to be OK. 1 with compound curves in it is still in the press, we'll see how that one goes, but it's not looking good. The one that was 2" out on a 12 inch span has actually gotten worse with steaming/clamping and will be thrown in the fireplace this weekend.

And it's not unique to this shipment. I've been back into HPR for almost 6 years now, and it seems like the last 2 years or so overall quality of things like tubes, ply, cutting, from many of the 'major' vendors has gone downhill. Heck, one of my rocket buddies just got a double $65 shipment of LOC tubes because they got a batch of 'bad tubes' where the glassine layer was bubbled like it had the plague.......but they sent them out anyway???.

I'm D.O.N.E. done with small batch 5 ply crap. I've been putting together balsa and ply RC airplanes and speedboats since 1980, and in the last 20 years I've built MANY vintage kits that have been stored in highly questionable areas of heat and humidity cycling like garages and attics, never once a warped piece of ply or balsa. Just this spring I built a TopFlite Holy Smoke 40 from 1985 that came out of a box that was so water stained that you could hardly tell what was in the box......every stick of wood in the thing was usable.

So I'm over whatever plywood stock that 'rocketry' vendors have on hand and I'm moving my money elsewhere. With somewhere around only 10K members of NAR/Tripoli, I wanted to keep my money in-house, as it were, but if every time you bought a dozen eggs from one of 2 vendors and 4 of them were broken and unusable, would you keep buying eggs from that guy, or try the other one hoping to get what you paid for THE FIRST TIME without having to "call and they'll make it right"?

I was just hoping that folks had good, reliable, tested sources of ply that they were happy with that they would pass along.

 

[Greg Furtman]

Menards has/had a kind of 1/4" underlayment, five-ply and flat enough that I made more than a few fins and centering rings from it. Pretty heavy, though. Sorry but I don't recall the name. We have a new Menards reasonably close by, and they have Baltic Birch in several thicknesses.

For Dobsonian telescopes the premier plywoods are Baltic Birch and Appleply, with Appleply being the top choice (no, it's not made from apple wood, nor is it an offshoot of Steve Jobs). A telescope mount has to be reasonably dimensionally stable, stiff, and reasonably lightweight. Appleply is all-hardwood, while many other types of plywood have hardwood veneer over softwood core layers. It's not cheap, though.

@prfesser I've been using Baltic Birch for Dob telescope mounts for 30 years. Great stuff. I've never used ApplePly as no one carries it in my neck of the woods. But if I remember correctly the internal plies are made of alder.

 

[KC3KNM]

I got 10 sheets of ply this week in 3 shipments from 3 different vendors, with 1 bad sheet in each shipment.

7 are fine, straight as arrows. Of the 3 that are warped, I steamed all 3 and clamped them. 1 has responded and looks like it's going to be OK. 1 with compound curves in it is still in the press, we'll see how that one goes, but it's not looking good. The one that was 2" out on a 12 inch span has actually gotten worse with steaming/clamping and will be thrown in the fireplace this weekend.

And it's not unique to this shipment. I've been back into HPR for almost 6 years now, and it seems like the last 2 years or so overall quality of things like tubes, ply, cutting, from many of the 'major' vendors has gone downhill. Heck, one of my rocket buddies just got a double $65 shipment of LOC tubes because they got a batch of 'bad tubes' where the glassine layer was bubbled like it had the plague.......but they sent them out anyway???.

I'm D.O.N.E. done with small batch 5 ply crap. I've been putting together balsa and ply RC airplanes and speedboats since 1980, and in the last 20 years I've built MANY vintage kits that have been stored in highly questionable areas of heat and humidity cycling like garages and attics, never once a warped piece of ply or balsa. Just this spring I built a TopFlite Holy Smoke 40 from 1985 that came out of a box that was so water stained that you could hardly tell what was in the box......every stick of wood in the thing was usable.

So I'm over whatever plywood stock that 'rocketry' vendors have on hand and I'm moving my money elsewhere. With somewhere around only 10K members of NAR/Tripoli, I wanted to keep my money in-house, as it were, but if every time you bought a dozen eggs from one of 2 vendors and 4 of them were broken and unusable, would you keep buying eggs from that guy, or try the other one hoping to get what you paid for THE FIRST TIME without having to "call and they'll make it right"?

I was just hoping that folks had good, reliable, tested sources of ply that they were happy with that they would pass along.

https://www.aircraftspruce.com/menus/wp/plywood.html
As mentioned earlier in the thread, Aircraft Spruce is a great source. Maybe a little expensive but everything I’ve gotten from them has been top notch.

 

[Banzai88]

https://www.aircraftspruce.com/menus/wp/plywood.html
As mentioned earlier in the thread, Aircraft Spruce is a great source. Maybe a little expensive but everything I’ve gotten from them has been top notch.

I'm willing to pay to get something I only have to buy once. Too many people are addicted to the $3 product that they buy once a year instead of getting the $10 product that they never have to replace.

 

[KC3KNM]

I'm willing to pay to get something I only have to buy once. Too many people are addicted to the $3 product that they buy once a year instead of getting the $10 product that they never have to replace.

Yeah, a club I was with bought a few sheets in the sizes we wanted and split shipping. Still was fairly expensive, but (take this with a grain of salt, I’m not a plywoodologist) everything we got was high quality and nice to work with. IIRC you can call them and have them cut up sheets or half sheets smaller to save on shipping.

 

[Buckeye]

Local woodworking supply. Look for baltic birch or cabinet grade ply. And woodworking supply isn't lowes or home depot. Its more like Rockler or Woodcraft but those are overpriced.

Agreed. If you have a Rockler or Woodcraft store nearby, at least you can look at the sheets before you buy. Pay the few bucks more and save yourself the hassle of being disappointed with mail order stuff.

JoAnn's Fabric. That is where I get my 1/8 and 1/4 inch plywood.

I have both JoAnn and Michaels near me. Michaels is completely wiped out of wood and the "manly" hobby supplies. I don't know if this is due to the pandemic or a shift in business model. I'll try JoAnn next time.

 

[RocketScott]

Edensaw

 

[WILDMANRS]

Woodcraft here in the Midwest

 

[teepot]

I've never received a bad piece of wood from Balsa Machining. I have also had good luck with Baltic Birch from Woodpeckers, which I get from Amazon.

 

[Buckeye]

...Seriously, the last 2 shipments that I've gotten from LOC and others has at least 1 out of every 3 sheets that's warped so bad you would think that it was cut from an English Longbow. I'm not even sure a human looked at them before shipping them, because no one in their right mind would send crap like that out the door.

And before you say "Just call 'em, I'm sure they'll send you replacements"...

I totally agree with you, and LOC seems to be the biggest offender. There are lots of forum threads like this: LOC sends damaged/incorrect parts, the buyer inquires, LOC sends replacements, and then the honor of "Great Customer Service!!!" is bestowed upon LOC. Well, how about getting it right the first time and spare everybody the hassle? The whole thing seems contrived, like LOC's business model is to push crummy quality out the door, hope that most people don't notice/care, work feverishly to please the complainers, and then collect the accolades.

I like LOC, but my experiences with them are about 50/50. I don't complain and just find work arounds. If they put more effort up front, it would go a long way.

 

[Banzai88]

I totally agree with you, and LOC seems to be the biggest offender. There are lots of forum threads like this: LOC sends damaged/incorrect parts, the buyer inquires, LOC sends replacements, and then the honor of "Great Customer Service!!!" is bestowed upon LOC. Well, how about getting it right the first time and spare everybody the hassle? The whole thing seems contrived, like LOC's business model is to push crummy quality out the door, hope that most people don't notice/care, work feverishly to please the complainers, and then collect the accolades.

I like LOC, but my experiences with them are about 50/50. I don't complain and just find work arounds. If they put more effort up front, it would go a long way.

Agreed. They seem to have changed to that business model under the new ownership, ESPECIALLLY bad in the last 2 years. It's so bad that I have Jason/LOC on speed dial for the almost $400 worth of orders that I've placed with them this year.

EVERY SINGLE ORDER was missing something, and about half of them ALSO needed replacement parts......but they've had things that I couldn't get from Mad Cow because they were out of stock with loooooooooooong lead times, or simply didn't offer.

Like I told Jason, I DON'T want something 'free' to make up for my troubles, I just want what I paid for the first time......without having to talk to you. Without having to ask for it AGAIN. Without having to be sent something that should have been in the FIRST box on the company's dime that gets shared out to everyone else in the way of higher prices!

I get it. Mistakes happen. But mistakes as a business model on every single order BUT making it right quickly is plain outright AFU.

The BEST customer service/warranty is the ONE THAT YOU NEVER NEED TO USE.

 

[Woody's Workshop]

The plies have to be cut green when they are that thin. They are glue and pressed with no dry time.
As moisture dries out of the wood, the wood shrinks and causes warping.
This is the problem with plywood. Oriented Strand Board was introduced as a cheaper, more stable building material.
Do some research, I remember reading there is one company that kiln dried thin veneer sheets for making model aircraft plywood. But that has been several years ago. Who knows if that company exists. It could have closed doors or sold out.
But it would seam to me someone out there must make decent ply that is dried before gluing up that is stable enough for model air planes.

 

[Banzai88]

The plies have to be cut green when they are that thin. They are glue and pressed with no dry time.
As moisture dries out of the wood, the wood shrinks and causes warping.
This is the problem with plywood. Oriented Strand Board was introduced as a cheaper, more stable building material.
Do some research, I remember reading there is one company that kiln dried thin veneer sheets for making model aircraft plywood. But that has been several years ago. Who knows if that company exists. It could have closed doors or sold out.
But it would seam to me someone out there must make decent ply that is dried before gluing up that is stable enough for model air planes.

Three rocketry guys on the high end of things have contacted me directly from the various FB threads on the NAR and Tripoli pages with their experiences in running rocket kit manufacturer businesses.

They've all said the same thing: The rocketry 5ply 1/4" that's so common is lowest common denominator junk and they all know it.....but it's at a price point that most simply accept it as lowest common denominator junk. The only thing that's kept it in service is that it's serviceable for what we're using it for much of the time.

The key seems to be higher end 12ply, and to buy from local cabinet shops if available. Or switch to sources of model aircraft higher count ply such as Sig.

 

[RocketScott]

Look for British Standard 1088 certified by Loyd's of London

Lots of Chinese plywood says that it's "made to 1088 specs" but it's not certified. I wouldn't trust it

Okoume, BS1088, Lloyds Certified 6mm

I have no experience with that company, it's just and example. I buy all my marine ply through Edensaw (linked to earlier) but they don't stock 6mm

 

[Rocks&Rockets]

Beware buying plywood sight unseen. It's like car tires of long ago. 4-ply used to mean they actually had 4 distinct and separate plus of cord rubber. Then they went to two plays and called the tires 4-ply "rated". HA! Gotcha! That's what I was told about the sample compared in the attached photos. "It is aircraft grade plywood"... The fin laying on the granite rock is from a kit I ordered last spring from LOC. Replacements were a little improved but still warped, and only 1/8th 3-ply. I dont buy cardboard-plywood kits anymore. I'll buy tubes from LOC because they are good quality but plywood comes from SIG or Aircraft Spruce.

 

[Banzai88]

Beware buying plywood sight unseen. It's like car tires of long ago. 4-ply used to mean they actually had 4 distinct and separate plus of cord rubber. Then they went to two plays and called the tires 4-ply "rated". HA! Gotcha! That's what I was told about the sample compared in the attached photos. "It is aircraft grade plywood"... The fin laying on the granite rock is from a kit I ordered last spring from LOC. Replacements were a little improved but still warped, and only 1/8th 3-ply. I dont buy cardboard-plywood kits anymore. I'll buy tubes from LOC because they are good quality but plywood comes from SIG or Aircraft Spruce.

Agreed. The 3 ply 1/8 and 5 ply 1/4 is crap for fins.

I'm developing this theory that the only real reason it's used is because it's cheap, available, and lasers well.

 

[Rocks&Rockets]

To the OP: Have you tried flattening the plywood? It was made flat and wants to be that way

...plywood doesn't flatten out with just a little weight. Trees Grow Round and want to stay that way

 

[RocketScott]

...plywood doesn't flatten out with just a little weight. Trees Grow Round and want to stay that way

The weight alone isn't the solution. It's usually a moisture issue. Weighting the sheet on a flat surface until the moisture content equalizes simply gives it a better chance of being flat

The OP steamed the sheets to try to straighten them out, probably introducing way too much moisture that didn't dry out evenly. Just a spray onto the convex side should be all it needs if weighting it down to even out doesn't do it