Timber Ax Mulcher Knive "JIG"

[Terra Firma Scott]

Timberax Owners present or past-

After numerous sharpenings "on the head" my knives are in need of a good facelift......either removing them and running them through some sort of milling machine or building a jig for a slow speed bench grinder to regain the original cutting angle across the cutting edge of the knife....

This could probly only be done a few times before the knive becomes a throw away..and they would all need to be taken down to the same spec to prevent balance issues...

Anyone with ideas?

 

[C.G.S.]

I sharpen my brush chipper knives on the surface grinder. I would think the knives would be to hard for milling machine cutters. The D-2 tool steel I make my Knives from is a slow process to sharpen but holds up 3 times as long as OEM Knives, also saves me $500.00 a set. So I would think you could tune up your blades nicely with the right setup. Sharp tools make you more money.

 

[Terra Firma Scott]

CGS-surface grinder meaning not a bench grinder? What stone or grit do you use and how do you keep them at the desired angle/degree of cut? a jig?

thanx

 

[C.G.S.]

80 Grit with coolant, the jig holds two knifes on the magentic chuck and the machine is auto feed across the table. It will put a mirror finish with a set keep within .001" or less if you want to get picky.

 

[Kyle_in_Tex]

Don't these things have carbide teeth?

 

[ClearViewGroup]

no the timberax does not have carbide teeth or hammers....different machines use different methods...knives...hammers...planar teeth etc...

as for a jig when i used to sharpen our timberax i would use a 9inch bench grinder and index them with the gauge provided...never got into the engineering that it sounds like some of you have...but it worked for us...its alot easier to do on a bench then it is on the head...

 

[Terra Firma Scott]

IM trying to picture how a bench grinder WONT shape the edge to like like a half moon...wont the stone/wheel cut the edge like a toe nail? trying to picture this.......

CGS-a surface grinder has a jig built in? or was this something you fabricated? I found a grinder made by JET that is water cooled and has a stone w/1000 grit and 400 grit...also has a jig holder but the accessory jigs appear to be for holding chisels,smaller knives,wood carving tools etc....the knives im sharpening are 5/8 inch thick.and over 9 inches long by 5 inches wide..wonder if they are magnetic also and if they will hold my large knives..

-sorry guys...

 

[C.G.S.]

Depending on the blade or knife material the grinding technigue can make a big defferance in how well the knife will cut and how long the edge will hold. Making blue spots on the edge means localized anealing and a loss in endurance. It can also cause cracking that takes the form of chipping along the knife edge.You can be causing alot of service life loss on chipper style heads if your burning the metal and using improper cutter angle. Unfortunately the wheel on a 9" hand grinder is hard to keep from burning the knife edge.That said more frequent lighter sharpings are better then less frequent heavier ones. Just like a chainsaw is easier to keep sharp then l get sharp after letting it get to dull

 

[C.G.S.]

Your Knifes are about like mine which are 4.5" X 12" x 3/8" Grinding wheel travels along the same plane as wheel rotation not perpendicular as with a bench grinder.

 

[Terra Firma Scott]

Looking for the manufacturer of the machine you use-thanx

 

[Landwise]

i have two sets of knives that i have been running for about 700 hours now. i have been looking into a milling machine.
right now i use a 4" grinder with 36 grit sand paper wheels, which conform a little better. I take them off the machine, place in a vise and use my eye and an angle finder to try to keep 35 deg.
one out of five times that i take them off, i have been taking them to a machine shop. at $350 per set, i will buy a mill soon. it took them a while to find the right bit and speed, but they do a great job. Rockwell on these things is around 58


just my .02

 

[C.G.S.]

Sorry I been away doing family X-mass thing. I'll see if I can't post a couple pics. I have two surface grinders in the shop and I have used both for knife work the small one is a DoAll with a 6"x18" magnetic chuck. The big one is a Gallmeyer&Livingston #55 with a 12"x36" magnetic chuck . Carbide Inserts on a mill would work as will but your jig and table would need to be real tight any chatter and the inserts would fail with that Rockwell 58 material. I have thought about trying that route as it would be faster then the grinder. But the automatic feed on the grinder means I just baby sit. I do use the CNC mill to make bolt slots and do the knife edge before they are heat treated. After that I always used the grinder, I have also thought about using the EDM machine to sharpen the knifes as well. It works well on the carbide on the stump grinder inserts.

 

[Terra Firma Scott]

Thanx for the info!....Landwise, Is "rockwell" the hardness of the metal?-or the point they start to blue?-or am i way off...also those pics would be great CGS..

 

[C.G.S.]

Knife grinders turn up on Ebay from time to time most need some work but it might be a way to go. Most milling of steel is done in a range 30 to 50 Rockwell. 60+ is file hard.What would be nice is a way to accurately sharpen them on the head. How long dose it take to change out a set?

 

[Terra Firma Scott]

My set consists of twelve blades...On and off in 10 mins with an impact gun..

Would be nice to build a jig that mounted to the head and as you say ACCURATELY true and sharpen the knives...

I have been sharpening only on the head but after hitting various objects and debris the knives loose their straight cutting edge and the 35 degree angle starts looking like 50 degrees..ha!