Lennox (pullmax) shrinking problems

[suhrsc]

Thanks everyone
I will take photos of the actual metal tonight...

and give the clay/playdough a try too if I have time

thanks
zach

[oldgoaly]

Zach,
I've seen a few problems over the years, one thing some people do is run the dies too tight, what gauge are you using and what gap between the dies? If you have .063, the gap has to be greater than .063, around .070 is good, remember the metal get thicker when shrunk! Another important step, some dies were designed to be set up with the rear of the dies flush, some others are not! Try starting out with lower die a 1/8" out the back farther than the upper. When shrinking feed the metal in fast and pull slowly out! funny how many do just the opposite. The only thing I see on your dies the upper die thumbnail recess the edge looks to be a little sharp. Now any movement, in / out or side to side in the dies will play havoc with the finish, and we are talking just a few thousandths, I've had a dial indicator on my T3 trying to find what was flexing or moving, it isn't easy! If you can take "good" pics of the pattern of the marking it can lead to a fix it is hard to get a good pic!. I always use aluminum to final check my dies, if it's good on aluminum, it will be good on steel. tt

[suhrsc]

thank you!

Here are a few photos....
I believe the problem may be in the missalignment of the dies?

Also a bit of a rough edge on the upper which seems I could polish off?

first 2 pics are hand turning the motor while feeding the aluminum....







this is a panel that I did to test.... you can see the marks in it... but it really did a good job of shrinking in a short amount of time... nothing was touched on the back 2"... front just shrunk then rolled in an English Wheel to level out...

[oldgoaly]

most definitely a sharp edge digging in, since it is on the top, look for it on the top die! (this isn't rocket science heck nothing blows up!) The edge of the thumbnail recess need to be radiused more, get that rounded over better, then you can smooth and polish them a bit. You will love them! tt

[CARS]

Did your stairs fall over???

[suhrsc]

haha... no stairs didnt fall over.... just some free ones i picked up

I got the dies figured out tonight... apparently the lower die was made wrong... the "flat" that goes around the raised thumb.. was/is tapered down towards the throat of the machine... inturn it was not compressing the aluminum correctly all around the "tuck"
i shimmed the upper die to get the flats matched....

still getting some slight tool marks because the dies arent polished... but... its working great!!!

I did about 4 passed on a piece of aluminum and get it to turn almost 90 degrees!
was experimenting a lot so theres some marks on it(pic below)...... but... all in all I am VERY impressed!!

a bit more fine tuning still... but I want to genuinely thank everyone who offered up advice!!

Thanks alot!!
Zach

[oldgoaly]

Zach,
when you get them polished a bit, if you have some die grease or plain wheel bearing grease, spread a thin layer on the lower die, then lower the upper so it just makes contacts with the lower die by hand of course. you should have a smile shape contact area just in front of the thumbnail. tt

[Tisdelski]

Hi Zach,

Make sure the die holders a exactly lined up, one pic makes the gap in the front looks smaller then in the rear.

Gary

[CARS]

Originally Posted by oldgoaly

Zach,
when you get them polished a bit, if you have some die grease or plain wheel bearing grease, spread a thin layer on the lower die, then lower the upper so it just makes contacts with the lower die by hand of course. you should have a smile shape contact area just in front of the thumbnail. tt

Terry, maybe this should be a separate issue, but isn't trapping grease going to lead to other problems? Like paint adhesion??

I know we are here to metal shape but most of us have a finished product in mind. (primer, paint, plating, etc.)

[oldgoaly]

Chris,
The grease trick is to check the actual contact points or sweet spot of the dies, this will show if the dies are properly aligned. I use the blue machinist grease and it turns everything blue if not careful. You don't need lube when using a pullmax style machine. I have heard of people using it nothing wrong with it. My gloves I use on the pullmax are oily enough to help lube a panel plus I spray sheets stored in shop with WD-40 so they don't rust or stick together. I'm sure a light oil such as WD-40 can help one see tracking patterns as some do wheeling.
Just looking at dies can give one a false impression, die grease shows you the truth! To me clay is rather thick, but if you use it all the time you know how to read it. You need at least 1/4" thick smile, smile should be just a few hairs wider than the thumbnail it's self. 1/2" thick is plenty if you get too much contact area then your cutting down on your shrinking ability. If the contact areas are to small you don't get as good of finish. Remember rule #1 it can not shrink if the gap between the dies is less than the thickness of the metal plus the amount of thickness gained when shrinking!
This is a reciprocating machine, not a Yoder power hammer style that has spring and flex coupling of the die. Critical gap like a english wheel, air planishing hammer more like a Yoder power hammer than a pullmax like machine. The big Baileigh hammer can do both ways well. Ben's and RichardK's designs are good too!