How I made a cowl steer blister............

First off, I apologize for my small cluttered work area. The hobby stuff is not the same priority as the money stuff. The side cover that I need to fabricate, will be made out of .040" aluminum. Sorry I don't know the spec number. It's a sheet that's been against the wall for quite some time.

I'm making this for a guy in our car club, who is building a Model A RPU and is planning to install cowl steering. Don't know what box he's using, and sorry, I don't have any photo's of his project. I will say that he builds some really nice stuff. Like most of us, he does what he can himself, and friends and club members help out where they can.

We all know that there are several different ways to fabricate a cover and the fabrication can be of any material you choose. He said he would like a polished aluminum cover and to follow the build theme, he thought rivets to fasten the cover would fill the bill.

I decided to build a hammer form for this, in case I want to fabricate additional covers. I had a short length of treated 2 x 12 left over from a summer deck stair repair, so decided to use that for the hammer form. The down side to this is that there was a fair size crack in the board, but I "beefed" it up with some scrap aluminum diamond plate. Normally, I don't think you would need to reinforce if the wood was not crap. Rather than using clamps for the hammer form, I decided to use 4 (1/4x20x3") hex bolts. I laid out my proposed shape ( about 4"x7") with a bit of taper towards the tail end, and transferred the shape to the board. Using a Bosch saber saw, set at a 30 degree angle, I carefully cut the shape. The top piece of the hammer form was cut about 1/4" larger than the bottom and no angle cut. I wanted the angle cut to give the aluminum a nice consistent surface to lay into while hammering.

I sheared a piece of the aluminum to size. Got the hammer form ready and before I begin, the aluminum needs to be annealed. For those who don't know, the annealing process physically softens the aluminum so it can be worked easier. There's a specific temperature the panel should be heated up to, but I can't tell you what it is. I can tell you that if you take a torch (no oxygen) and soot the panel up, then go over the panel and "burn" the soot off, you've annealed the panel. Got to take a break. Next post I'll start hammering!!! Stu

 

Can't wait to see the finished product.

 

The annealed piece of aluminum is placed into the hammer form and the form bolted tightly. Remember, I'm going to "move" and stretch this piece to a 2" bump with my hammers, so it really needs to be secure in the form. Some metal fabricators drill a couple of holes into the aluminum to "pin" the piece and keep it from sliding, however, by using this huge hunk of wood and bolting it tight, there should be no movement.

I'm hammering on my sand bag only because it's at a good work height. Later on, when the aluminum "grows", it will be hanging out of the form and resting on the bag. After 5/10 minutes, you can see the aluminum "sinking" into the form. I'll hammer some more and be back with more photo's. Stu

 

Bear with me......I'm a computer idiot. I'm sure there's a better way to post a tech, but I'm lucky to get it this good.

After hammering for about 30minutes, I'm busting the form open to let you see the actual progress. Normally, I wouldn't open it until I was finished, but I really wanted everyone to see the progress to this point. Back into the hammer form and about 30 more minutes of beating, now you can see the blister starting to peek out the bottom of the form. If it wasn't on the sand bag, it would have nowhere to go.

Needs a bit more persuasion, and then it will be time to planish the surface, or "fine tune" the blister. Be back in a few. Stu

 

Okay, out of the hammer form to see the result. Not looking too bad. Just need to fine tune it with a slapper spoon. When a dolly is placed on the backside of the work, and you "slap" it, you begin to see the surface begin to shine. The slapper brings down the high spots and the dolly brings up the low areas.

I'll do some more slapping and my next post will be TA DA!!! You guys can be the judge. Stu

 

After a bit more slapping, I think it's there. Sorry, but it's not getting the full polish until after our Hamb n Eggs breakfast tomorrow a.m. (maybe a show and tell event). I did one earlier and polished it. The polished one does not have the "teardrop" taper that I have on the one made this afternoon. Both done totally by hand (no fancy smanchy tools) in the same hammer form, although a bit different technique to achieve the taper look.

My vote is the teardrop taper, although, the other is nice too. Which ever one he decides is fine. Then I need to trim, leaving a nice lip for the rivets, and trim a relief slot for the pitman arm movement. Once I get this last one polished up, I'll post up a picture. Thanks for looking. Stu

 

Nice work! Thanks for sharing this


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nice! thanks for sharin.

 

That is really cool. Nice job... I learned a little somethin'.

 

Great work! Thanks for the "How to...".

 

Saweet man!

 

nice. I leaarned something today.

 

Now that is some nice work. Wish I could do that !!!! LOL

 

I love it when craftsmen show there work, and how to do it.
You sir are a craftsman, thank you.

 

Very interesting to say the least!! I may need to try this............

 

you the man Stu

 

Great job.

 

thanks for posting bill. who's building the rpu? can i call dibs on the one he doesn't want?

 

I made a blister for my transmisson tunnel (shifter arm hit the side) and i was miserable trying to control the shrinkage around the teardrop. Now i know a wood buck will solve all this..
Thanks for the tricks, great work..

 

The blister looks great and the ideas you laid out can be used to accomplish basically the same thing if someone wants to put the time in it,,thank you for posting. HRP

 

Pretty impressive for an old guy!

 

Why thank you. That's a great compliment coming from from a young kid. Stu

 

Rich Dickie from St. John, Indiana. Actually, The guys at breakfast (S.W. Chicago) this morning mentioned that you probably needed a steering cover. If you have your box mounted and know the amount of room you need, I can make one to fit your project. Are you at breakfast in Indiana next week? I've been wanting to stop by and see you guys, so maybe this is a good reason. Stu

 

i'll be at breakfast next week. i missed our breakfast this morning, had family in town and they wanted to eat somewheres else. val and i are still wanting to attend the sw chicago breakfast one of these days.
my steering is still in the planning stages but if you come to breakfast, we can drop by the garage afterwards and check out the T.

 

Looking forward to next Saturday a.m. in sunny Indiana. Stu

 

There is always a lot of gloom and doom in the news but with guys who have skills like this I venture a guess that we are going to be OK

 

Thanks for the Show and Tell this AM. Neat tech.
I still think that 3 bubbles on the skirts would be weird though.

 

Bobert, sometimes it's a lonely world for a trendsetter. Stu

 

Great tech Bill!
I see that you made it out of aluminum. I am thinking about doing a blister soon but thought about using carbon steel and not aluminum. I think I heard SK or AK carbon steel would be more forgiving to work with than cold rolled. I could be completely wrong. Dunno.

 

Interesting. I'll have to check and see how far a piece of 18 ga will move. Stu