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Polar Bear forge rocks!

Posted: Fri Apr 27, 2012 6:37 am
by Thaddeus
Last fall I contacted Jamie about getting a Grinder in a Box kit and after a couple of delays managed to actually scrape together the cash for it and put in my order. What arrived was a flat rate box weighing in at, well I am not really sure, but it was about as heavy as the post master could get over the counter. Inside was a variety of laser? cut parts neatly wrapped in foam and fitted in a wooden box. It was kind of like opening an iPod only geekier.

Then it got cold.

And the parts waited for warmer days.

Eventually the parts were assembled.
Taps were broken in inconvenient places, because they will not in fact 'go one more turn'.
And my grinder was born.

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This thing is a monster.
The motor is a 2hp terror from Wayne Coe.
It needs a VFD when I get enough cash up to buy one.
For now it has one setting. Kill.

So thanks to Jamie for providing a nice kit to the community.
One could probably build one from scratch with a little bit of study - but having all the main pieces arrive at once in a neat package is invaluable to folks like myself who need a bit of a push out the door. (It should be noted here that you will still need to buy wheels and various bolts and springs etc... oh and a motor.)

Definitely 5's across the board on the Freiman scale.

Re: Polar Bear forge rocks!

Posted: Fri Apr 27, 2012 7:57 am
by white mountain armoury
Sweet !!

Re: Polar Bear forge rocks!

Posted: Fri Apr 27, 2012 9:22 am
by Pitbull Armory
Hi there, Im guessing thats a Belt sander yes? How much did that set you backafter you bought all the parts? and how long to assemble?

Ty

Pb

Re: Polar Bear forge rocks!

Posted: Fri Apr 27, 2012 9:23 am
by Finnvarthr Finnbogason
I think I'm gonna have nightmares now. It keeps staring at me! Dude, throw that thing a steak or something. Quick!

Re: Polar Bear forge rocks!

Posted: Fri Apr 27, 2012 9:28 am
by GuntherofOrkney
nice work. even building them yourself from a kit these bad boys are expensive,i just happen to already have a motor and thinking about slowly buying the rest.

Re: Polar Bear forge rocks!

Posted: Fri Apr 27, 2012 10:04 am
by Johann ColdIron
Thaddeus wrote:For now it has one setting. Kill.
LOL, That looks like a fine fingerprint remover! One of these days I need to do the same.

Re: Polar Bear forge rocks!

Posted: Fri Apr 27, 2012 12:00 pm
by PatternWeld
A belt grinder doesn't remove finger prints, it removes MEAT. It does it before one's Lizard brain even makes them aware that something needed is missing.

That is gloves or no, even the heavy ones, even the kevlar ones.

And yes... when you accidently push something meaty into the side of the belt... it cuts to the bone.

The most fun to be had is when a belt snaps and slaps you at full speed as it winds off the drive wheel.

Seeing this built makes me want to replace the old BurrKing I work with.... This design is so much more versatile but if I was to build one, I'd want a rubber covered drive wheel and a variable speed motor.

Re: Polar Bear forge rocks!

Posted: Fri Apr 27, 2012 5:22 pm
by Thaddeus
I haven't tallied my receipts but I think it is in the ball park of $800-850 or so once I completed the build. Knife makers supply has a wide assortment of wheels available although I dont know it a rubber drive wheel is a specific option (rubber coated with a keyway). But I am sure its out there if you want it.
These were the cheepo versions of the possible wheels, and compared to some of the other grinders I have used they are quite loud so I expect I will be replacing them in the future.

I feed this thing finger tips which so far seems to keep it happy.
The VFD would make polishing tempered knives a little less of an anxiety ridden process.
I might do a three speed stepped pulley setup as an interim solution until I can save the cash I need to buy a variable speed unit from Wayne (who is fantastic to deal with as well - answers stupid questions without batting an eyelid).

Also the platen is a very ah... junkyard rig. I made it up from some angle iron that was mounted under the kitchen counters in my house and some scrap .5" plate steel. I am guessing its good old mild based on its sparks but I really have no idea. For now it's close enough, but eventually I will replace it with something I know is flat and squared up with the rest of the frame.

Oh, yes it is a belt grinder. It uses 2x72 belts which I am getting from Pop's Knife Supply http://popsupply.bizhosting.com/index.html

The next step with this grinder is to build a tool rest.
There have been a couple of situations where I have wanted one. I am trying to grind free hand as much as possible, but the results are not always as clean as I would like.
It's a learning curve I guess.

Re: Polar Bear forge rocks!

Posted: Fri Apr 27, 2012 7:34 pm
by Kenshin Hanabe
I'm actually building a 2X72, where do I get one of those variable speed controller?

Re: Polar Bear forge rocks!

Posted: Fri Apr 27, 2012 9:45 pm
by Thaddeus
I bought my motor from Wayne Coe http://www.waynecoeartistblacksmith.com/
He also sells the vfd units and has I think the best prices I have seen.

Re: Polar Bear forge rocks!

Posted: Fri Apr 27, 2012 10:07 pm
by polarbearforge
Nice build! It will definately take bits off of your hand that you would rather keep attached.

I don't believe Tracey has a rubber coated drive wheel. I've never found it necessary on any grinder that I've built.

Wayne is a good guy to do business with. He does have really good prices on motors and vfd's.

Jamie

Re: Polar Bear forge rocks!

Posted: Sat Apr 28, 2012 1:50 am
by Samuel
may want to put some ply up behind it to cover the window:D cause if your luck is anything like mine thats the FIRST thing that is gonna get busted:D ( I set up my first buffer in an old garage, polished a half gauntlet with it and the wheel grabbed it, shot it 12 ft away and off the floor right into the garage door window.)

Re: Polar Bear forge rocks!

Posted: Sat Apr 28, 2012 6:56 am
by Thaddeus
It no longer lives there, it was the convenient clean spot of the moment while I was doing the final fit up for the platen.
The bench it was on was too high for the proper 'belly buck' grinder position.
The bench it is on now is really too flimsy and I want to make up a more solid platform for it.
I need to get a hold of a chop saw and start frequenting the drop pile of my local metal yard. (which is just over an hour away).

The rubber wheels are really meant for contact use.
I want to eventually get a 2" contact wheel to switch out with the small aluminum wheel on the bracket.
But I expect the trade off is rolling resistance. And it certainly is a lower priority than the variable speed unit.

Actually the next thing I would like to do is partially break it down and paint it a blue to match the motor.
Does anybody have any idea what color that might be in actuality?

Re: Polar Bear forge rocks!

Posted: Sat Apr 28, 2012 10:12 am
by PatternWeld
Sounds like I should explain for benefit of Jamie & Thaddeus ...

The reason I want a rubber treaded drive wheel is simple. As any grinder ages, it will need periodic "tune ups". Belt tracking will wander some over time. This is partially controlled by a "crowned" wheel. It doesn't take much, just a few thousandths.

With a rubber covered drive wheel, you can maintain a very "square" contact grinding wheel while being able to adjust that "crown" very easily.

Now as to that platen... Get yourself a piece of 1/4" thick G-10 carbon fiber scale. Countersink your mounting screws and epoxy it to the face of your platen. Done.

Happy grinding gents.

Re: Polar Bear forge rocks!

Posted: Sat Apr 28, 2012 12:17 pm
by Thaddeus
Hmm, not sure I get it still.
Mine has a crowned drive wheel.
It is sort of ablative, the wheel has a textured surface that is gradually wearing smooth.
The tracking wheel is also crowned, and wearing down. I figured that they would just require replacing eventually.

The carbon fiber scale idea is great! I will definitely do that.
Thanks for the tip.

Tracy may in fact have the rubber drive wheels you are looking for, or be able to source them.
You may already have their site on file, but for others here it is. http://www.usaknifemaker.com/

Re: Polar Bear forge rocks!

Posted: Sat Apr 28, 2012 4:04 pm
by polarbearforge
I've always crowned my idler wheel. (The ones from usaknifemaker are also this way.) The only time I use rubber coated wheels, is when I am going to grind against them. I periodically adjust the crown of my idler. I don't use the safest procedure (I file it while the grinder is running).

I recommend a hardened piece of tool steel for the platen. I usually use A2 or O1 at 1/2" thick or better. I do all my machining beforehand, and then through harden it. I've ground against a variety of materials before, but never g10.

Jamie

Re: Polar Bear forge rocks!

Posted: Sat Apr 28, 2012 4:57 pm
by PatternWeld
The old hands used to use Micarta but like G-10 it can and will wear. Some guys even use the super high temp glass... The idea is that it practically eliminates the "Slap & Pop" from the belt seam when you use the platen for flat grinding.

If you plan on using the platen for general grinding then for sure go with the A2 or O1