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The Newbies Arena Are you new to knife making? Here is all the help you will need. |
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#16
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Thanks guys!!!
All of these tips are an asset. As I'm learning, it's harder than one thinks! I cut up two more pieces of stock tonight and spent an hour and a half making fun.
They are getting better already! I removed the workrest tonight. Also, I took a tip and for the initial coarse cuts, a wooden stick with a small ledge to hold the knife and support it out towards the end. It doesn't have the feel of bare fingers, but it sure saves the burned fingers and helped me stay grinding for more than five seconds. I was able to get a feel of staying in the groove. I also found that running the machine faster in the coarse grit helped cut quicker and cut away some of the heat. It then started throwing sparks. Before, it was me throwing out expletives! After getting close to what I wanted, then I took it barehand, and was able to get a nice consistent curve before the heat got up there. I'm certain I would do myself a favor by changing the belt already. It's probably dull. Also, it's an 80 grit, not a 36 or 50, so it is going to take more time. I also did better by sitting down. I was hunching over trying to get to the center of the wheel on a 32" workbench. I also see the benefit of having a larger wheel for a wider blade. There must be a fixed width for each diameter wheel that is effective for a hollow grind. Depending on the width of your blade and the style of your cut, would warrant the change. Little by little.... Thanks again! Coop |
#17
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Coop,
Several of the knife supply houses sell a little slide chart showing the resultant curvature of a hollow grind with different size wheels. I think they cost abot $ 10 +/-, and are a good reference. |
#18
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If you search the old threads on the CKD, you will find a spreadsheet that was done by Ben Ogletree. Very helpful.
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#19
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Coop, A trick I found to refine my hollow grinding skills is to grind a blade from hardened steel. I had a commision for a 12" fishing knife, thin for that length, to keep it from warping Paul Bos suggested profileing it and drilling tha holes in it, then heat treating and then grinding the hollows. This worked so well and it showed what I was doing so well that I learned a lot. Kinda like slow motion, you could use a wore out file or what ever you want that is hard, you may even end up with a viable knife in the process. For this I would start with 60 grit then go to 120 grit.
Hope this helps. Also I can't practice on anything that has no value, just a little on scrap then dive right in, I finish almost all knives I start, very few rejects. I think it is a mind game with me. Gib |
#20
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Practice, practice, practice...
That's the overriding message I hear from everyone I talk to. You would think I've had a bunch of time to do tens of blades, but my schedule has been especially busy, and it's taken me over a week just to get back there for this:
I did the double-sided thing for support and convenience. What you see is two different styles with an attempt to repeat them on each side. That's the hard part! The easy part is to bungle the plunge cut (or bevel? what IS it called?). I slipped on one twice and made a mess. That one would be the 'thinner' knife after I would grind the face, he, he... I used a wooden support stick for the initial heat-producing cuts, then taped my thumbs and dipped often for the rest of the cuts with bare hands. The added 'handle' really helps. Still on that 80g belt. Not looking for a bunch of kudo's here, just keepin' you guys and future newbies posted. It's going to take me some time before I produce a finished knife, but you can be sure you'll know. Bob will GET his buck! Coop (wait till I get the platen up and start flat grinding questions! Groan..... ) |
#21
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Now that's tremendous progress from the examples which I saw just a few days ago!
With sandpaper and elbow grease, you could easily move on to finishing blades from here. Don't grind the blade to an edge before heat treating - leave at least 0.020. Given the speed with which you've made such progress with hollow grinding, I don't think you'll have any trouble with flat grinding. |
#22
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Jim, You are making fantastic progress, your grinds look great. If you change to 120g you will slow things down so you can see what you are doing better. Hope this helps, Gib
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#23
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Basic hollow-grinding technique
You guys need to give awards for the dumbest question of the month.
Some expensive new power tools would be nice . . . ! But I'm sorry, I'll waltz away with the dumb award this month: For openers, all y'all call a belt sander a "grinder", and I'll bow to your unusual nomenclature. But, what I want to know is whether ANYBODY EVER hollow grinds on a REAL GRINDER - as in "bench grinder" - as in a chunk of rock bolted to the shaft of an electric motor? TELL ME PLEASE I don't have to go out and buy an expensive big BELT SANDER, with a 8" - 10" idler wheel, if I want to hollow grind! Tell me, please, I can do it on an old-timey electric rock bench grinder! Thank you very much! Gene |
#24
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Gene,
'Grinder' is truly short for Belt Grinder. A bench grinder would be extremely hard to control and would build up heat way too fast. The point of the 2 X 72" belt is that you can use a variety of grits running around either an 8" or larger contact wheel. While it gets hot, it is a much slower buildup of heat. It also works at a controllable rate. You can also easily work on both sides of the wheel to keep the grind even. There is lots more to than that. I'm sure that others will have a better explanation. Bob Sigmon PS - I think that I have been cave diving in the Mayo area, it was about 5 years ago, so I'm a little foggy on the names of the cities that we were in. |
#25
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It could be done with large, slow moving and water cooled wheels, like old cutlery shops, but I don't think I'd want to try with 3400+ rpm bench grinders.
Profiling a blade from a tool rest should work OK, then, maybe some initial stock removal, followed by a lot of hand filing should produce a decent flat "grind". |
#26
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Three major problems with a stone,
#1 is heat, a belt runs MUCH cooler. #2 is grit changes, a real hassle on bench grinders. #3 is wheel diameter changes on a stone, too much hand work to blend.A belt grinder keeps the same wheel diameter, and can change grits quickly. |
#27
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basic holl-grinding techniques
Thank you Bob, Kelly and Geno, for your great help!
You didn't give me the answer I WANTED, but I'm certain your reply was what I NEEDED to hear, namely: I'VE GOT TO GO OUT AND BUY A BIGGER BELT SANDER TO DO MY HOLLOW GRINDING! Next time you come to Mayo (or Live Oak) to do your cave diving, Bob, look me up! We even have a secret grotto on our own property, and no one has ever been down in it! This is a little out of thread perhaps, but would it be permissible for me to ask you guys WHICH PARTICULAR bottom-of-the-line belt sander I need to buy to do this hollow grinding? I'm only a poor old rickety amateur knifemaker - NOT A BIG FILTHY RICH, WORLD-FAMOUS, KNIFEMAKER LIKE YOU DUDES - so I can't justify spending a fortune on a sander. What should I buy? Thank you, thank you! Gene |
#28
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Gene-
That question gets asked over and over from every guy who wants to buy his first knife grinder. It's been answered many times in these forums. Go back to august 12th in this "Newbies" forum to "a new Grinder" and you'll get off to a good start... Dennis Yeah Baby! |
#29
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Gene,
Follow Dennis's suggestion to a long thread on this subject. I like my Bader variable, with all the bells & whistles, but they are expensive. Prior comments suggest that the Coote is a very good, moderately priced belt grinder. Grizzly is cheaper, but lacks some versatility. There must be some used ones out there, but I've yet to seen any advertised for sale. |
#30
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Gene,
While looking around go to Log Cabin Forge , Stan makes a nice grinder that starts at $550. An 8" Contact wheel is $125.00. I have one of his grinders and it works very well and is setup right out of the box. Just another alternative. Bob Sigmon |
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blade, fishing knife, forge, knife, knife making, knives |
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