Forming new Snowmobile Ski bottoms

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Model T Ford Forum: Forum 2016: Forming new Snowmobile Ski bottoms
Top of pagePrevious messageNext messageBottom of page Link to this message  By Zachary Carrico on Friday, January 08, 2016 - 11:15 pm:

The first two installments of this were originally posted with Chad's non-Snowmobile T-Ski restore thread. On good advise that some snowmobile folks might be interested but not check the other thread I am starting a fresh thread for 2016 with a Snowmobile heading.



Top of pagePrevious messageNext messageBottom of page Link to this message  By Zachary Carrico on Friday, January 08, 2016 - 11:16 pm:

So here is what I am up to thus far; this fall I picked up a set of original snowmobile skis. The skis could have been run as found but the outer edges of the metal bottoms have seen many years of hard use (I assume from delivering mail and hitting the edge of curbing? pavement seems less likely?)
A few weeks ago metal forms were cut from some large pieces of hard maple on the band saw after tracing the bottom of the original ski wood as a pattern, then decreasing the radius of each curve to account for spring back in the metal. The cutting operation was heavy even with two people on the band saw... A number of 9-1/2" x1/2" bolts were ordered from Fastenal and yesterday the two halves of the cauls were bolted together.
After a great deal of wrench turning with the maple creaking and crushing under force of some home made wood clamps and 1/2" threaded rod things looked pretty good:





Top of pagePrevious messageNext messageBottom of page Link to this message  By Zachary Carrico on Friday, January 08, 2016 - 11:19 pm:

The bottoms of the original skis are at just about 7-8 degrees. My clamping caul is at a 10 degree angle to account for some spring back in the metal, next time I will pre-bend the "V" in the ski to 10 degrees so the metal can flatten some during the second forming process it was somewhat less this time, otherwise things fit acceptably:




Here is a shot with new, old and wood for comparison.




A messy workshop is a well used workshop right? -That's my excuse anyhow.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Zachary Carrico on Friday, January 08, 2016 - 11:36 pm:

Here is the simple pieces I made up that will force a new plow bolt trough a pre-drilled hole to form dimples in the metal.



Here they are mounted in my old punch press. I do not have a proper hydraulic press to dimple these on so the press is being re-purposed. This application may be pushing things a bit but the C at the back is at least 12" deep by 6" wide so the frame isn't going anywhere.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Zachary Carrico on Friday, January 08, 2016 - 11:47 pm:

Here are the results on some scrap cut off the ends:


With original plow bolt:



Back side:



The dimple doesn't have as crisp of a square as I would like, but that is because the new bolt I am using to form the dimple with has a very low profile square section, I think it will be sufficient though. The head sits just a bit below flush with the test piece of metal. Tomorrow I can move along with dimpling of the skis


Top of pagePrevious messageNext messageBottom of page Link to this message  By Burger in Spokane on Saturday, January 09, 2016 - 12:51 am:

Are you using heat to help form your metal ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chad Marchees _____Tax Capital, NY on Saturday, January 09, 2016 - 07:17 am:

Might as well finish it up this year Zac. Between the two of us, I am convinced there will be no snow this year---although you may have a couple inches at your house.

I wonder how they formed the ski bottom originally. You can see the compound curves in that setup, and now I fully understand what a pain that must be to make. Did you have the metal braked down the center first before you put it in the form?

If the workshop is too neat, then two things are happening, no work is being done or your retired and have all sorts of time to clean. That's my story anyhow. I have been slowly trying to clean mine up a bit, it is out of hand again. I can fully say that there is a lot of work happening out of that shop.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Zachary Carrico on Saturday, January 09, 2016 - 09:06 am:

Burger, no heat just cold formed and lots of pressure, it is 10 ga metal.
Chad, they were brake bent before the compound bend was added, the form of course has both bends so that the v is retained.
I should be able to pick up the second set of bottoms Monday, I dropped off steel to be bent Thursday afternoon; then my trailer will have matching skis if I ever make time to cut up some wood for the upper part


Top of pagePrevious messageNext messageBottom of page Link to this message  By Zachary Carrico on Saturday, January 09, 2016 - 09:31 pm:

Dimpled the skis, Trimmed the ends, ground one skis ends. Maybe some paint tomorrow.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Russell Nave on Saturday, January 09, 2016 - 11:24 pm:

Those skis look great! I hope you get snow, I was wanting to attend the Vermont event again this year.
Its looking good here in California for local snow. Hopefully get to christen the Snowbird soon,


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chad Marchees _____Tax Capital, NY on Sunday, January 10, 2016 - 07:18 am:

Zac, is there any type of skegg on the bottom other than where the metal was metal braked in half?

OT, Is the term brake or broke, the metal is not broken, but brake sounds weird as past tense.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Zachary Carrico on Sunday, January 10, 2016 - 07:43 am:

I am hoping to attend Vermont, it is about 2-1/2 maybe three hours from here my brother lives within maybe half an hour. last year I had planned to drive up with the kids, but everyone got sick the week before.
Chad I don't think the term brake applies to the action of metal being bent just to the device causing the action? IE: The metal was formed in a brake giving it a roughly 10 degree bend prior to the compound bend being applied to the ski.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chad Marchees _____Tax Capital, NY on Sunday, January 10, 2016 - 08:11 am:

Sometimes, some words meanings just don't translate well to past tense forms.

So back to my other question, is there a skegg on the bottom like mine? or does the 10 degree bend supposed to be enough to be the skegg.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Zachary Carrico on Sunday, January 10, 2016 - 03:13 pm:

Oh, Sorry, there will be a skeg, per the original, that is the hard part to define... each ski has a different skeg on it. I emailed one of the Snowmobile members, he said that they had different arrangements....
Carefully inspecting the ski with a full skeg, there is evidence that it originally had a 2/3 length skeg if you look in the images above you can see a rectangular hole about 2/3 of the way up the ski, looking more carefully you can see that there is a piece of metal protruding through, this is actually the very tip of the skeg, it is not original, you can see where there are still original rivets that were never popped out of their holes some alternate holes were made for the new skeg. interestingly the holes continue past the rectangle, evidencing that the ski was drilled to accept either style. The old rivet heads only extend forward as far as the rectangular hole, in operation the rivets would be clamped by the wood and could not have fallen out over the years, I take this as evidence that there were never any.
The full length skeg on the other ski looks like it is an original that was installed as a replacement, I didn't notice this right away, but the wood of both skis are chiseled to accept a skeg that passes through the metal bottom, both have a mark showing where the original skegs pressed against the wood a bit so I am taking that as pretty solid evidence that the originals were only 2/3 length. Further, I find it implausible that someone might have worn through more than two sets of skegs and I suspect the shorter skeg was replaced later than the full skeg maybe after a time when a replacement was available because the full skeg is quite worn, and the replacement is still thicker than the original would have been.
It appears that the 2/3 skeg is 36-38 inches (I forget what I measured) from tip to tail riveted every 4" starting 1/4" behind the square hole for the skeg tip.


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