Ski Builders Forum

I've been out of town for work for almost a month, just got back a few days ago (only to find out today I'm leaving again next week, d'oh).

While away I did a lot of thinking about making my autofeed for my grinder, and with the help of some new tools (Grizzly metal lathe, and a grizzly mini mill), I'm cooking away and making this thing reality.

(if you don't know about my grinder, check it out here... http://www.skibuilders.com/phpBB2/viewt ... 23e7dfa220 )

So for starters, I needed a small AC motor, so I went to harbor freight in search of some thing with a motor I could use. The cheapest and smallest thing I could find was a trolley for a gantry crane.

Next I purchased a 60:1 worm gear from Ebay. The mounting holes on this just so happen to almost perfectly match up to the bolts that hold the motor together, so mounting the two together was a breeze.

The motor needed some work. It had a spiral cut gear on the output shaft, which wasn't going to work. So I ground that down completely, welded a big blob on the end, then turned that down on the lathe to a perfect cylinder.





Next I bought a driveshaft from McMaster that fit in the input of the wormgear, and that had to be drilled out to fit over the output shaft of the motor.



To fix this "adapter" to the output of the motor, there wasn't enough clearance to put a setscrew in there, so I machined a slot and am using a woodruff key.



And tada! Here is the motor mounted to the wormgear, with the output shaft/feed roller on it.





Works like a charm. The only issue now is the feed roller is 4", which is about the same size as the wormgear housing. So now I have clearance issues with the ski. One option would be to have the motor way out to the side, but structurally I don't like that, so I think I'm going to have to order a larger feed roller (a 6" one is like $90 ). That way the motor can be nice and snug with the feed roller.

Last I took the wheels from the gantry trolley and turned those down (mostly just to practice on the lathe more, this is my first lathe so I'm still learning). I am going to use these as bearing supports that an arm will pivot from, the end of that arm will have the motor/roller.

Before on left, after turning on right





With bearings pressed in, and holes drilled for mounting.



Tomorrow I'm going to build the frame structure that will support this whole contraption, and then I'll be waiting again until I get the new roller before I can proceed (and by that time I'll probably be leaving town again for work )

More updates to come soon!

I made great progress today, I realize the pictures I posted probably make no sense, so hopefully these pictures will help make sense of all of it.

First of all I realized I left out some pictures of the adapter thing I made so here are some more to illustrate what I had to make.

After I had welded the blob on the end of the motor rotor shaft, I turned it down on the lathe to this



Here is the motor with the freshly turned output shaft, and the gearbox input on the left



And here is the adapter on the end of the motor shaft, with woodruff key





So the motor and gearbox are happy together. Now on to the meaty stuff.

Here is the swing arm freshly welded. It is two 2"x2" square steel bars welded together sideways. The business on the left end there is for mounting the gearbox (in a few pictures). The shaft on the right side goes in the bearings to pivot from.







I then drilled the mounting plates for the gearbox, and bolted that on.





And here is a rough check of how it will sit on the ski grinder.











Just two things to note on the last few pictures... the feed roller driveshaft will obviously be cut down so that the roller is over the middle of the belt. Also that roller is 4" diameter, which is too small because the gear box rests on the belt. I will be receiving a new larger (6" diameter) feed roller tomorrow, that is also twice as wide (4" wide). That should make things perfect.

All that is left is welding up the base for it, that will bolt onto the top of the grinder itself (using two existing holes for fences, and drilling/tapping two more holes). I will also be adding an adjustable stop to keep it from dropping onto the grinding belt.

This thing weighs a ton, and if it turns out its too heavy (putting too much pressure on the ski) I will add an arm that extends past the swing arm pivot, with some kind of weight that can be slid and bolted in place, so that the pressure is adjustable.

OMGHG!
Holy sweetness. Yeah you will want a counter weight to fine tune the amount of downforce. Nice work Looks major pro from here.

Realy well done!

Nicely done!
wish I had a lathe and welder...

redbull wrote:Nicely done!
wish I had a lathe and welder...

Definitely worthwhile investments I started with a fluxcore wirefeed welder, and it was a great way to learn. Going from that to my MIG was amazing though, much easier.

I've only had the lathe a week and it has changed my life (along with the mini mill). I feel like I can do anything now!

Hey man! With these skills you're pretty close to "coremaster 3000"! (as discussed in another thread)

Good work!

OAC wrote:Hey man! With these skills you're pretty close to "coremaster 3000"! (as discussed in another thread)

Good work!

I've already ordered some of the parts Once the autofeed is done that's my next project (I should probably make some skis at some point instead of making tools...)

twizzstyle wrote:(I should probably make some skis at some point instead of making tools...)

hahaha, i keep thinking that all the time! drawing up a cnc-mill in cad as i type

chrismp wrote:

twizzstyle wrote:(I should probably make some skis at some point instead of making tools...)

hahaha, i keep thinking that all the time! drawing up a cnc-mill in cad as i type

NICE! I got a set of small stepper motors and a controller box off ebay two weeks ago, planning to rig them up to my mini mill just to figure out the process (the software side is the thing that will hold me up). Then maybe next year after skiing is done for the season I'll scale it up and build something large enough to do cores and bases.

The other thing I was halfway considering was putting two stepper motors onto my manual edge bender, how sweet would that be? But for the amount of skis I make (one to two pairs a year) it's probably not worth the effort.

Dang! Are you a machine shop or ski builder? Really nice work and talented to boot! We'll be looking for top notch equipment to come out of Twizz's shop.

Way to go!

skidesmond wrote:Dang! Are you a machine shop or ski builder? Really nice work and talented to boot! We'll be looking for top notch equipment to come out of Twizz's shop.

Way to go!

I test new airplanes This is just what I do for fun at home

Hey twizz
I spent a lot of sleepless nights thinking about building a CNC edge bender. I basically got to the point where I had worked out a design and worked out the mathematics that relate incremental movements of the mobile wheel to change in radius of the bend. I was pretty excited about it all until I used my edge bender (same like yours) and realised I got a fair amount of springback and that I had no idea from a software point of view how to "tune" the equations so the end result would actually bend an edge that would resemble what you were trying to achieve
I gave up. I sleep a lot better now!
I think with your mill you could build a really good replacement for the drill press vice to mount your wheels to and this would form the backbone of a great little machine.

Ski building is second behind cessna restoration at the moment. At least some skills are transferable like repairing the fibreglass on the nose cowls today with epoxy and chopped matt. Hopefully back in the air by Christmas.

falls wrote: Ski building is second behind cessna restoration at the moment. At least some skills are transferable like repairing the fibreglass on the nose cowls today with epoxy and chopped matt. Hopefully back in the air by Christmas.

Awesome!!! I don't get to do any physical work on our airplanes, I just fly in them.

You've read my mind on all accounts. With all the spring back in edges, I would probably have to go through a lot of sacrificial edges to get the thing calibrated for this setting gives you this final radius of bend, etc. That wouldn't be too hard at all I don't think, I'd just waste a few sections of edge material.

Whether or not an automatic edge bender would be "worth" all the effort, it would still be a fun project for the sake of a challenging project (as is with everything I do... like the autofeed). It's not like its hard to run a ski on a grinder by hand... the autofeed is just badass

Autofeed is done, minus paint and some small adjustments.

I haven't tested it yet with the grinder running, my neighbors have some visitors over, and I don't want to be "that guy" running really loud machinery at night (the grinder is loud). I did some testing without a belt and one of my homemade skis just running on the bare metal belt thing.

It seems to work great, although I think it may need a larger motor. I can tell the motor is working kind of hard at times (may be easier with a grinding belt, or might be harder).

There is a threaded rod on the swing arm that acts as an adjustable stop so the feed drum doesn't run into the grinding belt, works like a charm (need to cut down the excess threaded rod, can do that later).

The drum isn't exactly parallel with the grinding surface. While functionally this will be ok, and it still feeds the ski, it bugs me, and once things are wet I want the most contact I can get for best grip. I might have to bend some metal, or slot some holes, but it shouldn't be too hard getting them exactly parallel.

As an added bonus, I can swing the entire thing out of the way if I want to use the grinder by hand without the autofeed, without unbolting and removing the whole clap-trap - awesome!

Pictures!





















Video:

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