Register now to get rid of these ads!

Pinching model A frame rails at the firewall

Discussion in 'The Hokey Ass Message Board' started by brianangus, Apr 9, 2008.

  1. THE FOLLOWING RESPONSE WAS TO A GENTLEMAN FROM IRELAND, WHO WANTED TO KNOW THE PROCEDURE FOR "PINCHING" A MODEL A FRAME AT THE COWL: Hello James---Welcome to Canada---Your not intruding. I am going to assume that you still want the stock width front and rear crossmember, and that you plan on some custom body mounts.---The body mounts are an angle that set on the outside edge of the frame, so if you suck the frame in 1" per side, the outstanding leg of the angle, along with the holes in it will have to be extended by 1" to maintain the same position relative to the body. Since all of the other crossmembers will be removed except the rear crossmember and the front crossmember, you could conceivably use a boat builders clamp at the point where you want the narrowing to occur, and start tightening.---A boat clamp is a pair of castings fitted to a peice of 1" pipe. one casting is the moveable jaw, and can be slid to whatever length you need,then locked there, the other casting is attached to one end of the pipe and has a moveable jaw which is moved along parallel to the pipe with a crank mechanism and an acme thread. (I have a pair and can send you a picture if you want.) You do not say if the frame is boxed or not, (I hope not) and will structure my answer based on the assumption that it is not boxed. The big trick is to be sure that you bend each frame rail by exactly the same amount. I would set the frame up on 4 boxes about 16" high at each of the 4 corners and level it and check for squareness before I started bending anything. Use a plumb bob and a chalk line to establish a centerline on the garage floor that clearly marks the centerline of the frame on the floor. Use an oxy acetylene torch with a big cutting tip or a rosebud tip, and heat one frame rail at a time to a cherry red in a band about 2" wide exactly where you want the bend to be, before using the boat clamp. ---Be especially sure to get a lot of heat into the top and bottom flanges, as this is where the most resistance to bending will be. As soon as one frame rail is cherry red, put the boat clamp on, and start tightening untill the heated framerail moves in the required amount---It will bend very easy when heated to cherry red, and the unheated framerail will not bend. Be very carefull during this operation that you do not move the frame around on the boxes relative to the centerline, as this is your "witness mark". You will need a 24" level, and probably a carpenters square, to measure exactly how much bend is enough. Leave the boat builders clamp in place, and walk away---let everything cool for an hour. go have a beer. Then come back and remove the boat builders clamp. and repeat the heating and bending operation on the other frame rail. Measure, measure, measure, and then measure one more time to be absolutely certain that you have bent both frame rails the same amount, relative to the centerline. Walk away---leave it for an hour. Do NOT quench the heated rails with water, oil, or blasts of air. that should get it done---It wouldn't hurt, if after everything is levelled, but before you start the heating and bending, to place a 100 pound bag of sand on top of the frame rail at each corner where it is supported on the box. This will lessen the chance of inadvertantly bumping the frame with your knee and moving it away from that very important centerline, and will also ensure that the frame stays flat and level during the heating process. I would also put in a temporary support under the frame rail about 12" on either side of the zone where you are doing the heating on each frame rail, so that they don't "sag" under their own weight when heated to cherry red.---Brian (I have added this to my "how to build an early hotrod frame" post)
    __________________
     
  2. And this my friends is a boat builders clamp. I inherited these from my dad. Back in the 1950's, we used to build wooden rowboats.--One a week, all summer long. These clamps were used to clamp the two sides (generally 1" x 16" pine) to the transom of the boat, untill we got it glued and screwed into place. Then came the difficult part---putting a brass woodscrew every 2" all around the perimeter of the boat to hold the plywood bottom on. On a 12 foot boat, that worked out to something like 170 screwnails, all screwed in by hand. (we had no electricity then). By the end of summer I would have a pad of callous 1/4" thick on the palm of my hand, and could arm wrestle and beat kids 3 years older than me when we went back to school in the fall!!---Antways, they are also great for hotrod building!!----Brian
     

    Attached Files:

  3. Rusty
    Joined: Mar 4, 2004
    Posts: 9,473

    Rusty
    Member

    That is what I use on a 32 frame. I use about 4 of them after making the cuts. Make it real uniform and easy. Tried heating and if you are using American stamping it wont work just heating. I had both rails cherry red and they did nto like it. So I put about 8 slits 1/4 inch apart. Made it reall mice anmd smooth too

    Rusty
     
  4. Dirty31--I find that for a relatively mild pinching (3/4" to 1" per side) no cuts are necessary. If the top and bottom flanges are heated sufficiently they will "spread" enough without cutting.
     

  5. Kevin Lee
    Joined: Nov 12, 2001
    Posts: 7,582

    Kevin Lee
    Super Moderator
    Staff Member

    I'm confused - why would someone want to pinch a model A frame?
     
  6. Kevin---I don't have the faintest idea. Maybe the guy meant a 32 frame??? Anyways, the same method will work for any frame, so I wasn't too worried about it.---Brian
     
  7. Home-made frame puller-together and squarer-upper.

    1" x 2" x .120 wall rectangular tubing, 1/2" all-thread, four nuts & washers and a couple of coupler nuts.

    [​IMG]
     
  8. Good Plan C9---Way cheaper than buying boat builders clamps. I always had them, so never had to inprovise.---Brian
     
  9. Primo
    Joined: Nov 7, 2004
    Posts: 425

    Primo
    Member

    Kevine Lee - I'm pinching my A frame, when its done I'll post why I did it and if it did what I thought it would...

    Brianangus - Every time I see one of your posts I learn something, this should help me alot. I've seen Evilone0528's frame you helped layout and it is pretty awesome.

    - Primo
     

  10. Thanks.

    Good part is way less of a struggle to get the clamps on and squared away.

    I left the pipe behind when I moved to Arizona, but brought the clamp parts along.
    They're buried in the shed.
    And will probably stay there for awhile.

    Sweetie wants me to build another teapot display cabinet for her collection.

    Once was enough.

    I like wood, but the darned stuff is hard to weld....:D
     
  11. Paul
    Joined: Aug 29, 2002
    Posts: 16,389

    Paul
    Editor

    I used bar clamps to pull the rails in when pinching the A frame for my T

    I wanted to channel the body over the rails
    with the pinch right at the firewall

    I also straightened out the stock "pinch"
    and then pinched them again at the rear of the body

    so the rails are parallel from horn to firewall,
    taper out to rear of body
    then parallel to the rear crossmember


    edit;
    here's a link
    see the first few pictures and descriptions...

    http://www.jalopyjournal.com/forum/showthread.php?t=102832
     
  12. DrJ
    Joined: Mar 3, 2001
    Posts: 9,419

    DrJ
    Member

    I got some of them bar clamps at Harbor Freight.
    It's a 'kit" you add a piece of galvanized pipe. your choice of length.
    If you don't have them, or the hardware for C9's rig, you can also cinch stuff together with a turniquit of rope or cable with a bar or pipe in the middle to twist it tight like the rubber band in a model airplane.
    Remember that if you put stuff in tension and the tensioner breaks, or slips, that stuff is going to turn into a catapult.:eek:
     
  13. Willy301
    Joined: Nov 16, 2007
    Posts: 1,426

    Willy301
    Member

    Also remember not to use rope that will melt or burn if heating metal to get it to bend. I also inherited quite a few pipe clamps,but they use various sizes of pipe diameters. Some must be way old.
     
  14. Smallfordsuk
    Joined: Jan 8, 2005
    Posts: 56

    Smallfordsuk
    Member
    from Belfast

    As the guilty party from Ireland - I intend to put a T modified body onto an A frame however it needs to come in a bit in order to channel the body over the frame - Have to say a bog thank you to Brian and Paul for the prompt reply to my query - had it roughly in my head how to carry it out but better to get the experts view - This place rocks

    Many thanks to all James
     
  15. One thing to add about the home-made gizmo above, it's very useful on 32 style frames in that the frame sides are not completely vertical in the stylized areas as stamped and the clamping part can be at a small angle so as to square up the frame proper.
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.