Bullneck frame machining

[BigLakeBob]

Great stuff Steve. I assume the front mount and rear mount will be positioned to the correct height in relation to each other for the engine used, but do you have any problems after machining the rear motor mount of dropping the engine too low in the frame? I recently had a problem of this where it was almost impossible to remove the squish exhaust pipe because the engine sat lower in the frame. Keep up the posts!

[Steve Little]

G,day mate. Nice to have you taking part.
I have never had that problem with squish pipes. Was the underside of the frame section damaged or flattened?
This entire frame that I am machining has been pulled apart but I am assuming you recut the decks of an assembled frame. Out of interest, (and for future reference) how much did you take off the decks?


I can give an answer why this frame won't have issues in that area, but making my answer legible, but not too wordy will be my challenge.


Here goes;
This customer is the young guy from Melbourne who bought my frame jig, straightening table, and springer straightening jig. So I know what his frame jig can do.


The faces of the front and rear engine mounts, bolt up to the jig.
Even though I cut metal off them, the new faces of both these loose components will bolt up to the jig which is made to factory blueprint measurements.
The brake cross over tube will sit 0,030" higher because I cut that much off the rear engine deck, and when it bolts up to the jig, the cross over will sit higher but won't adversely affect anything because the crossover support is also loose and can be fashioned to fit around the tube before welding.
The two control plates that are bolted to either end of the front engine mount will sit 020" higher...but have no negative impact on any fitment.


Leg wetting fact for anyone who plays with big twin Harley frames:
I have posted this information a few years ago, but a repost for some of the ADHD kids will be beneficial.
There is a crucial relationship between the angle of the rear engine deck to the seat post that must be exactly correct. When the angle between these two is correct, the front engine mount can then be welded in place.
Hmm!! Not as wordy as I thought.
More tomorrow.

[Rooster]

I'm always amazed at the engineering that went into these machines. So many people say "Oh, it's a Harley. There's a lot of room to shim and adjust."
Not true. While there are certain tolerances, "shims" are usually required on frames that are bent, warped, twisted, or tweaked from use and/or abuse- which is very very common, especially knuckle frames with lighter tubing. I'm convinced nearly all frames on the road are not as they left the factory.
I am always accused of being too anal with my repair work, but there are so many subtle relationships between components that an error in one place can cause trickledown problems. (If that makes any sense.)
Thanks again, Steve, for this informative and interesting thread.

[Steve Little]

This fixture was made many years ago and I was fairly proud of it at the time.
It was for machining one axle carrier at a time but did both “left and right” axle carriers.
As you can see it has been ratted for parts, and the likely suspect was probably the cnc guy.
He wasn't interested in machining one part at a time and made a fixture that carried 4 axle carriers at a time was used in conjunction with the rotary table on the cnc.
I was not going to try and work my way through the cnc process, so I bolted this cnc fixture to an angle face plate on my traditional mill and went at it.

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I used an original set of axle carriers to clock the tooling in. When I had the tooling lined up at the correct angles of the holes in an original, I then fitted one of the axle carriers to be cleaned and drilled the tubing out and then finished it with a 6 flute end mill for a more accurate finish.


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You might be able to see the witness mark, where I stopped and did a small “side shift” in the cut?

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[Steve Little]

Time to machine out the seat post. I will have to be creative during the alignment and set up of this one.

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This drill fits neatly in here. Now I just need to clamp it right here... somehow.

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Woooh neddy!! Before I start setting up for some drilling action, I have to remove the seat post plug so that the drill can pass all the way through.

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No matter what repair needs to be done to a seat post, it is always a rotten, messy job.
All done.

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[Steve Little]

Was a little nervous so I pulled the nuts down to 2 million foot lbs. Took a deep breath and cautiously put the first drill through.

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Surprisingly, the job sat nice and solid through the procedure.

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First drill through was 1 1/4” which cleared the stiffener and then 1 1/2” which took care of the seat post.

Now to set up the last piece for cleaning.

[Steve Little]

Used the side of the 1” end mill against the tube to get the datum, and then set my digital readout. Then it was a easy side shift to center up for the cut.

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No prizes for guessing what is going to happen here.

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No point burning up my tooling unnecessarily. Now were ready to drill out some tubing. I'm glad the customer didn't keep cutting with the slicing blade. He has just slit through the tack weld but if he had kept going...half a tube would have been a bit more challenging to clean up.

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[Steve Little]

Last tool through was a 1" 6 flute end mill.

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labour of love ,some hours have gone into it so far

No love. Just flat out concentration and my aim for a professional finish.
Setting up fixtures and clocking them in for single part machining, is very time consuming.
I stopped charging him at 35 hours (add another 10) and dropped my rate from $100 an hour to $70.

I have received some messages asking if I am back in the frame business.
Sorry. Iv'e done my time there, and I'm happy with the level I got it to.
I helped to spawn a couple of talented businesses ...Craig Clack in Tennessee USA. And Race Frame Engineering now in Japan.
These people are talented and made the time to come over here to learn the biz.

Hope you enjoyed the show.

[nuklhd]

steve, thank you. I have never seen work like this performed before. I appreciate I can look over a masters shoulder and that you take us along thru the steps.

[Steve Little]

steve, thank you. I have never seen work like this performed before. I appreciate I can look over a masters shoulder and that you take us along thru the steps.

Thanks. I appreciate it, but feel a bit uncomfortable with the term.
More importantly..what are you still doing awake?

[Rollo]

Steve,
I have a question for you. Now that you have cleaned out all these castings/forgings and in doing so eliminated the splines that were in them originally is there any danger that the casting/ forgings are too thin and do you need to re-spline then to get a good connection between the new tubing to be installed and the casting/forging. I was told the splines helped secure the connection as some very small portion would get into the splines and help hold it. I know you are an expert at this and would assume that whatever you do is okay but just curious. Some engineer along the way must have felt the splined connections were needed unless it was an over engineering design.
Thanks

Tom (Rollo) Hardy
AMCA #12766

[Steve Little]

Hi Tom. Thanks for your interest.
The straight knurl is machined onto the tube, not into the hole. The witness mark you can see inside the holes is from the knurl on the tube. Each tube has a few thou clearance when the frame is put together. When the parts are heated up for brazing the brass is drawn along the space between each knurl. The external part (the forging) is open to air and cools down faster than the tubing within. Standard principle of a metal hole cooling down is contraction. i.e. the socket shrinks onto the internal tube. Hence the witness mark inside the socket.
The same principle happens to an electrically welded socket...but the shrinkage rate isn't as dramatic.
So a short answer would be; The locking action of the knurl does not happen until the weld cools down.
A side note. We used a knurling tool in the lathe but I don't know that Harley did. The following is an educated guess... The knurling on HD tubes is so precise That my thought is that HD might have used some kind of two or three piece press tool that clamped onto the tube and pressed the knurling mark.
When we used to mill drill the frame components (before the cnc came along) we generally used 6 flute end mills, because they offer more stability during drilling holes and give a tighter tolerance on the hole.
When the tubes where knurled, we controlled the height (stand up) of the knurl by the pressure applied by the tool in the lathe.
If anyone has any questions, feel free to ask

[larry]

I've always thought that the purpose of the knurl was to ensure that the brazing flowed the entire length of the joint.

[Rollo]

Steve,

Thanks for clearing that process up. I know you know what you are doing but some of us try and speculate and we usually get it totally wrong. You built a frame for a 41 knuckle with side car I needed a few years ago but when we talked you recommended doing the thicker pan head tubing and I'm glad we did it that way. Just wish you were still at it but understand why you aren't. Think I might give Clack a try as I see some others have with good results as I have another 41 frame that is a mess and basically needs to be disassembled and the above process on the casting/forgings and new tubing installed. Again thanks for your input and guidance and craftsmanship and hope it catches on.

Tom (Rollo) Hardy
AMCA #12766

[Steve Little]

I've always thought that the purpose of the knurl was to ensure that the brazing flowed the entire length of the joint.

G,Morn'in Larry.
In my mind, I thought I had described that, but my answer lost some of its emphasis due to tired ramblings. I got sidetracked with why the knurl eventually locks onto the steel. I shouldn't compose and post answers at 12 30 am.
Why were you awake at 12, 30am you may ask? My daughter is doing year 12 and coming up to exams. I was helping her with stuff and eventually tripped off to bed at 12. My mistake was turning my iPad to try and wind down.