Formblock

[nborer]

Step 1 compete: my shop is organized and ready to start pounding out ribs - it’s not much, but it’s enough space to make parts before I have to start kicking cars out of the garage. Not all is in the photo - my bandsaw, mitre saw, and a few other goodies are on rollers next to one of the cars. My wife has already told me that it’s my car that gets kicked out of the garage first...

Now, onto step 2: make the formblock. I just purchased Eric Newton’s wing manual, and followed his web page for many years prior to getting here (if you’re reading, Eric, your excellent web page helped to start my obsession with the Bearhawk over a decade ago). I’ve been planning to go with MDF, but am a bit wary. I made some cornhole boards a while ago with MDF, and they hold up well, but the corners sure do show some wear. How will it hold up after a few thousand hammer blows? I’ve seen pics on this forum with folks using plywood, hardwood, and the like. Any favorites? Eric seemed to be pretty happy with the MDF... though it looks like 3/4” is the best I’m going to do at my local Lowe’s or Home Depot...

Formblock cutting starts next week! I’m excited to get started! Only one or two decades to go...

[Bcone1381]

I used MDF. The raw edge of the block needs to get treated to shore it up. I think I applied a thin coating of 5 minute epoxy on the edge with a putty knife. It got some slight damage with normal use, and that is easily repairable with a Bondo product that has some fiberglass strands mixed with it.

[S Lathrop]

I made a single form block from 1" maple. I had a print made of the Mylar wing profile drawing and glued that to the maple then cut and sanded. Another term for form block is "slapping block", because that is what it is used for. I made many more blocks to form all the wing parts but they were all taken from the master slapping block. Having the drawing on the master slapping block proved to be very handy.

[spinningwrench]

Use Hard Maple and it will stand up well to the blows.

[fairchild]

NB---
I used MDF--- glued 2 pieces of 3/4 together to make a blank. then cut out the block and used a radius cutter in the router to cut the edges.
then I did multiple coats of "wood hardener" on the corners and about 1 inch inboard of the corners. That stuff strengthens the corners quite a bit. still working OK.
Also you can get a nice smooth finish on it where it is coated. Also prevents it from absorbing moisture.

T

[nborer]

Thanks all. Have primary and backup blocks nearly complete, will look for wood hardener to keep the edges true. I used a spindle sander to get it close to the line and flat, and then a small block of wood with a 1/16 radius to sand the edges. Y’all are starting to make me think I need to dust off the router... have one I have barely used, and I don’t have a table built for it. May make the other blocks go faster I suppose.

[way_up_north]

Thanks all. Have primary and backup blocks nearly complete, will look for wood hardener to keep the edges true. I used a spindle sander to get it close to the line and flat, and then a small block of wood with a 1/16 radius to sand the edges. Y’all are starting to make me think I need to dust off the router... have one I have barely used, and I don’t have a table built for it. May make the other blocks go faster I suppose.

I’ve seen some fellows use super glue or epoxy or wood plastisizer to ad strength to the edge of softer woods...or just use a hard wood no added chemicals needed...thou it cost a lot if new....

MDF seems to work great with no treatment

When you're driving around and you see a hardwood table in the trash it should gleem like gold in your eyes...lol

myself I use 1 inch Baltic birch..with super glue on the edges....I get dizzy from mdf dust

BUT....if you can find it the holy grail of form blocks is made from DuPont corian residential counter top material....local kitchen re-modellers might have scrap sitting around....it is indestructible....the only problem is restaurants love this material as cutting blocks.... So there is a strong demand for this even 2nd hand

maybe others can correct me here... but I never really pound on the edge to set the radius... I use glancing blows on the flange near the corner edge... I think of it more like pulling the metal around the corner... the metal finds its own shape


May I recommend for the discerning builder...

a really cool tool is the flange tool the RV guys developed to get the flanges to their final 90 degrees ...you can make this yourself....

This Bearhawk builder has made 2 versions of this tool...the typical RV rib flange tool....and the other has a genius modification...he Bearhawked it....take a look

The RVs use 6061 I believe from memory......the angle in the tool might need to be set a little steeper because we use 2024....

materials list and plans(keep in mind the tool needs to be sized for our rivet/fluting spacing).... Rib Flange Straightener


Some history for this tool time travel back to 2009 for its origins...from the RV guys...

http://www.vansairforce.com/communit...ad.php?t=51247

[fairchild]

I mostly only use a small and large dead-blow rubber hammer for manual edge bending. I also have a big UHMW sheet metal forming hammer I use a little if I want
to "set" the beginning of the bend line. I added about 4 layers of black tape to the face to pad it a bit. NO MDF edge deformation so far. All done with all 30 nose ribs and the dies look perfect. (my hyd press does the first 3/4 of the bend--- dead blows for the rest --- the the RV tool to finish the bend to 90 degrees.)

i found it works better to use the RV tool BEFORE mashing the fluts. (not the other way round)
Tim

[nborer]

Been waiting for a warm day where I’m not working to apply the wood hardener, but otherwise formblocks are complete. This work thing is really interrupting my building! I have a dead blow mallet, plastic mallet, soft face hammer, and ball peen hammer for forming. I suspect I’ll mostly use the dead blow and plastic mallets for most forming. Was planning to bob-stick the flanges (thanks for the videos!) as I don’t have a press handy.

[way_up_north]

Been waiting for a warm day where I’m not working to apply the wood hardener, but otherwise formblocks are complete. This work thing is really interrupting my building! I have a dead blow mallet, plastic mallet, soft face hammer, and ball peen hammer for forming. I suspect I’ll mostly use the dead blow and plastic mallets for most forming. Was planning to bob-stick the flanges (thanks for the videos!) as I don’t have a press handy.

Good morning

just a friendly reminder on the ball peen hammer....you probably know this already but not to use this on aluminum without some protection on it....as it will put iron into the aluminum and cause disimilar metal reactions..... essentially rust particles into the part....

Some builders use a bronze hammer to avoid the iron into the aluminum thing....

All my previous build experience is with all aluminum planes....something I don't know is if it's ok to use the ball peen un protected on the 4130 steel parts of the rest of the plane...it's dissimilar alloys then ....if it matters ...

Maybe a more learned colleague will chime in with an opinion...

[way_up_north]

Step 1 compete: my shop is organized and ready to start pounding out ribs - it’s not much, but it’s enough space to make parts before I have to start kicking cars out of the garage. Not all is in the photo - my bandsaw, mitre saw, and a few other goodies are on rollers next to one of the cars. My wife has already told me that it’s my car that gets kicked out of the garage first...

Now, onto step 2: make the formblock. I just purchased Eric Newton’s wing manual, and followed his web page for many years prior to getting here (if you’re reading, Eric, your excellent web page helped to start my obsession with the Bearhawk over a decade ago). I’ve been planning to go with MDF, but am a bit wary. I made some cornhole boards a while ago with MDF, and they hold up well, but the corners sure do show some wear. How will it hold up after a few thousand hammer blows? I’ve seen pics on this forum with folks using plywood, hardwood, and the like. Any favorites? Eric seemed to be pretty happy with the MDF... though it looks like 3/4” is the best I’m going to do at my local Lowe’s or Home Depot...

Formblock cutting starts next week! I’m excited to get started! Only one or two decades to go...

I could not remember where I saw the wood hardener/liquid plastic used...then I was re-watcing a fellow Bearhawk builders(fairchild) video and voila.....minwax wood hardener

at around 12 minutes he talks about it. I`m going to try some of it out myself it looks very interesting.......looks like a nice fusion of 2 materials...plastic and wood...

This video integrates a lot of technique, his blocks have the fluting and rivet spacing marked on the blocks so you can easily transfer them to the rib...and the lightening hole angle routered in. use of the flange straightener...its a great scratch building video...if you dont have a press like he does...you can use the bob stick.....

Well worth a watch.

[nborer]

Glad to know I picked the right stuff! I picked up Minwax wood hardener last week and just applied it tonight (had time and enough warm weather to leave shop doors open) before I saw this post. Thanks for sharing!

I’m planning to cut the rest of my jigs from the now-completed master formblock and will switch my bandsaw over to the metal-cutting blade when those are done.