Chopper Frame Stress

[Riddle]

I was talking to a buddy the other day about building a chopper frame from scratch. I have the plans for the frame and the jig, and was just asking him for some insight. He then told me to use only ChromeMoly tubing and to have it "destressed" after it's welded.
After reading this forum and others, I haven't found anyone mentioning destressing the frame. Does anyone here have some insight?

[hardtailjohn]

The "destress" issue has been argued since the very first weld was ever made, I think! Some do, some don't... I've seen some VERY high stress tubing engine mounts that aren't "destressed" after welding (Piper Aerostar, for one...) and in 20+ years, haven't seen any stress cracks. On the other hand, I've seen stuff that was supposedly "destressed" by heating it red hot then slowly pulling the flame away, and have seen them crack...or not.. (how's that for wishy-washy?). I read a book sometime ago, called High Performance Welding, or something similar, and he states that you don't need to worry about it.... I tend to agree. I'm sure you're going to hear alot of other opinions, but I'm just sharing mine. By the way, I build/restore antique aircraft for a living, and work with 4130 as well as 1020 tubing almost every day. I also ride a Harley Chopper (with an Ironhead XLCH engine, so we're talking vibration) and haven't ever had any trouble with welds that haven't been "destressed".
Good luck, and keep us posted on your results, please.... I've found that I'm never too old to learn something new...
John

[Sam Lee]

If Chrome Moly is welded under the wrong conditions,it can get brittle.Stress relieving will solve this problem,if you can find an oven big enough,but you risk warping the frame. :shock:
Using the correct preheat,and the proper filler rod,will give you the best possible weld without being brittle.
IMHO mild steel would be a better choice,especially for the street,and you wouldn't have to worry about it being brittle or stress relieving.Chrome Moly SOUNDS good,but is more trouble than it's worth.
I'm sure the EAA site has some info on welding Chrome Moly if your still interested..

[Riddle]

Actually, I was thinking Chrome Moly was overkill. Everything i've read suggests that the ERW tubing is just as good, if not better.
Thanks, you guys for the prompt (and insightful) response. I'd be lost without you (sob, sob).
Well, gotta go write some cheesy 80's lyrics. Later

[no999gr]

DOM tubing is really nice to work with . I believe you can get it in 1018,1020, and 1026. You get cleaner bends because the thickness is more consistant than ERW tube. I use it for leading link forks,sidecar chassis , and swing arms. It welds easily , and is plenty strong for M/C frames. --RG

[Riddle]

Do you know a good source of DOM tubing? I was going to use 1¼" OD / .120 wall. This project is still in the "money" phase. I need a notcher and a bender. What I have found so far will cost about $800.00 all together.

[no999gr]

Here is where I get it. http://www.tubeservice.com/ There is probably some place closer to you. --RG

[Jason93]

Riddle, you definately will have enough strength with DOM .120 wall. Thats what I use and I havent had a problem in 3 years. Make sure you make an accurate jig, your motor to tranny to rear wheel alignment is crucial if you want a reliable bike that goes down the road straight. I usually run S&S 124's (125-130HP) in the frames and they hold help quite well. It would definately be easier for you to purchase a frame from a cost perspective, its prohibitively expensive to build just one frame. But I'm sure you have your own reasoning. Either way keep us all posted, I'd love to see some pics when you get started. Thanks.

[luckeyeth]

what's the going rate for DOM that size anyhow?

[sollis30]

I was talking to a buddy the other day about building a chopper frame from scratch. I have the plans for the frame and the jig, and was just asking him for some insight. He then told me to use only ChromeMoly tubing and to have it "destressed" after it's welded.
After reading this forum and others, I haven't found anyone mentioning destressing the frame. Does anyone here have some insight?
Chrome- moly is no goof for frames with V twin engines becouse of vibration

i know what you gonna say ,what abouth NHRA bikes , they run only for copple seconds and allways been check constantly

use DOM tubing for you frame