TOPIC:

Total deformation or flatening of the tubing was .035" down to .965 from the original 1" diameter

Next up will be a 1.5" test roll.....tomorrow

Motor Head wrote:

Its a real science the exhaust, much effort to beat most production systems as they will do much R&D to get a product to market. I would have expected a different distance between the mergings in that system, not much between the first and second or the second to 3rd. Take a look at some of the automotive makers and you will see what I mean. I have only built 1 for a Isuzu Diesel I had 4.3 SOHC no turbo. Followed another that I had bought for a Toyota motor, and bought some mandrel bends to help fab it.

No argument here, but there isn't quite as much room under a bike as there is under an Isuzu or a Toyota

see if you can come up with some square dies for the roller ,then you can get really creative.another optionwith square tubing is to slice it down the middle and bend the shape you want and weld it back together with no kinks

HF does in fact offer a seperate square die set for $50 or so. It's listed as a 1/2" die and interestingly enough, the square die is made of 4140 cromo while the round dies are cheap cast steel

porchev914 wrote:

Total deformation or flatening of the tubing was .035" down to .965 from the original 1" diameter

Next up will be a 1.5" test roll.....tomorrow

Yeah let's see it! Looks promising so far... Are the bigger dies all the same radius or are the bigger tube OD dies bigger radius as well?

OK, I've got some more pics and test info. To answer your question Sander, the OD of the dies are all the same @ 4".

Another note worthy item are the bearings. Contrary to HF's usual use of cheap bushings, the dies ride on sealed bearings, but there is only one set, so you have to swap the bearings when you swap dies.

Here is my first bend on 1.5"

I started with a 48" length. I should have counted the number of cycles it took to get to this point, but I didn't I brought it around to 42.25" in length. You can see the deformation of the tube at the ends where the dies stopped.

I layed it next to my Yosh to give you an idea of dimension

That first roll yielded a deformation of the tubing to a tune of .41" down to 1.459". Considerably more than the 1" at the same radius bend

Considering how much the 1.5" deformed at such a large radius, I am wondering if I reduced the amount of pressure on the die for each cycle I would experience less deformatiom. Now that I have started crushing the tube a little more than I wanted in the first large radius bend, I thought I would try a secondary, tighter bend at one end to see how much worse it'll get. The sencondary bend, while not much tighter of a radius, kept deforming more than I would have liked. A .66" deformation down to 1.434"

This is how the bends look set next the my header

Here is a close up of the end, so you can see the amount deformation at the tighter end of the roll

Next I'll try to roll a piece using smaller increments of die tension to see if that makes any difference. After that, I'll cap, fill and compact a tube with sand and run the same test to see if there is any change.