morso-like chopper

Allen Stover

True Grumbler
Mar 5, 2004
Columbus, Ohio
When we took over the shop I'm running about a year ago part of the inventory was a Pistorius chopper. Very similar to the Morso. (Do they get the green paint from the same place?) Anyways, I just had the blades sharpened and picked them up last thursday (5 days ago). I was cutting a piece of poplar strecher stock that I get from Old Grange, and the D*#@ thing chipped on me. I was being a good boy and "nibbled" through, but at about the 4th pass, I noticed that it wasn't cutting as smoothly. Is it really possible that a blade that should be able to cu through oak would get cought up on poplar?

I'm going to take this back to get it re-sharpened, but I've also heard of potentially better blades out there... any thoughts?
There were blades on the market that were manufactured in Japan and in the former Yugoslavia that were both fairly high maintenance. I got a pair of each and retired them after the first sharpening. The steel was way too soft.
The Danish steel blades for Morso and Jyden are far superior IMHO. They are also considerably more costly, but as with most things, you get what you pay for.
I buy mine from a company called Tech Mark ((501) 945-9393) in Little Rock, Ar. I don't know if they have blades for Pistorius, but I would think that manufacturers original equipment would be best if available, and thats pretty much all they handle. They won't even sharpen the generic blades, says it mucks up the sharpening stones.
I wouldn't think it would happen with moulding but it's not uncommon for wood to have metal in it. I run a metal detector over the wood I use for guitars before running through a plainer, joiner, or thickness sander.

I would guess it did just chip. I have never had one do that either but I suppose it could happen! If you had them hollow ground I would guess they would be more likely to "chip" but again I've never heard of it. The only chip I have had with my chopper is the time I cut through a v nail. I deserved it.
Soft woods may not cut smoothly on a chopper even with the sharpest of blades. An old timer called it Punky wood. I've had liners that couldn't be cut cleanly with a saw or chopper.
The Pistorius Chopper is manufactured by Dans_List which also manufactures the Morso. The machines are identicle. The blades are also one and the same. if you are having a problem it because the blades were not sharpened correctly. They are genuine Morso blades.
Thanks everyone.

The blades were indeed hollow ground, and I had a feeling that this might have been the culprit...
Allen, I don't understand your statement about hollow-grinding being "the culprit". My understanding is that the genuine blades can and should be hollow-ground. Since having this done by Tech-Mark I have had far better performance from my Jyden chopper.

:cool: Rick
Hollow grinding is done with a wheel milling across the face or perpendicular to the cutting edge. The results is a thinner blade at the working edge. That is why when your first slap them in the chopper, they cut like a surgens blade in butter. BTW scaples are also hollow ground; that's is why they are also now "throw away after single use". Because they are rapidly useless. My surgeon nephew says he makes no more than one cut longer than 4" with a blade then pitches it. Skin is tough, but moulding is tougher.

"Flat" or "Table" grinding will heat the metel less in the sharpening thus leaving the ductul strength in the blade. Where the hollow is a rapid heat producing grit wheel that grinds away metal and produces a lot of heat. Enough to cause tempering of the leading edge, which is also now thinned below design thickness.

The cutting grind of a knife, chisel, or plane blade it about 25 degrees. Hollow grinding can reduce that angle to under 22 degrees, which dulls faster and becomes more brittel.
If a knife blade is hollow ground, a "micro angle" needs to be established at the working edge. The grind of the Micro angle should be greater than 25 degrees but not to exceed 30. This will add some strength to the working edge.

But with all that, the best is a Flat SLOW WET ground face that you should be able to see yourself in, both the grind angle, and on the flattened and polished back.

Allan, somewhere in all my stuff, I have a chunk of liner moulding with a civil war musket ball imbedded in it. Luckily I just nicked it, then had it x-rayed by a doctor customer. He framed the x-ray, I kept the chunk of liner.

The hollow grind that Tech-Mark puts on chopper blades provides by far the best result I've ever seen. No doubt the life could be lengthtened by adding the micro bevel, but we cut hundreds of frames out of maple and oak before needing them to be re-sharpened.

BTW, a lead musket ball will not hurt your blades. We've hit dozens of all sorts of bullets over the years with various wood cutting equipment without any negative impact. But speaking of interesting things encased in wood, about a month ago we came across what is the most unique I've ever seen. It's a walnut board that has two walnuts embedded into it. They must have fallen into a crotch and they never rotted before the tree grew around them. We discovered it as it came out of the planer, and it has an almost perfect cross section of one of them. I've been collecting odd bits of wood for twenty some years and always wanted to build a cabinet to display them. I think I'm going to incorporate this piece of walnut into the cabinet itself.