Question Ragged corners

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braggingrites

braggingrites

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Sep 20, 2011
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Pleasanton, CA
I seem to be getting ragged corners (on the side of the frame, not the top) from my chopper. Is it probably just dull blades, cheap moulding (happens more on some mouldings than others) or that's life with a chopper?

I have a really small shop and don't have the room (or $$ right now) for a saw. How can I get cleaner chops? It's driving me crazy - I'm spending a lot of time puttying and I just think it looks bad.

Any advise would be great. I have a used Jyden chopper that seems fine.
 
Life with a chopper is actually wonderful if you follow the rules.

  1. Blades have to be sharp.
  2. Chopper must be adjusted correctly.
  3. Chips are cleaned out every week in small shop.
  4. NEVER use any kind of oil - - only pencil (graffite) marking on mating surfaces.
  5. When in doubt - refer back to #1 & 2

If #1 is taken care of, then you just need to adjust the leading edge until
it is just past the plane of the backer walls. (this is done by loosening the
large glan nut underneath and moving the headstock.
 
I never liked to lube the blades because that lube will transfer to the wood and not allow the glue to adhere as well.
 
Many of the wood mouldings we are buying these days are made on species that do not chop well, even with freshly-sharpened knives. When you experience chipping of the finish or shredding of the wood, use a saw with a sharp, 80-100 tooth carbide-tipped blade.

Any sort of oil on the mitered wood surface could affect the glue's bonding strength, including fingerprints and oil-based color markers. Lightly sanding the miters usually removes any residue that could cause problems.
 
There is a lot of stuff nowadays with a really thick and brittle compo coating. Not only does it chip along the back, it dull the blades very quickly which makes it chip more. :party:
 
Baer Charlton said:
Life with a chopper is actually wonderful if you follow the rules.

  1. Blades have to be sharp.
  2. Chopper must be adjusted correctly.
  3. Chips are cleaned out every week in small shop.
  4. NEVER use any kind of oil - - only pencil (graffite) marking on mating surfaces.
  5. When in doubt - refer back to #1 & 2

If #1 is taken care of, then you just need to adjust the leading edge until
it is just past the plane of the backer walls. (this is done by loosening the
large glan nut underneath and moving the headstock.
Click to expand...

I have morsol blades! My frames in my new job crumble and they never used to in my old one so i know something is up! i have my blades sharpened and its seems A LITTLE better. New job driving me crazy and it never used to be this difficult. i have doubts the are being sharpened properly... can you give me any advice!
?
 
What kind of moulding are you using? I have a 40-something-year-old Jyden chopper which I love, but a lot of today's mouldings (as Jim Miller pointed out above) are made of crummy woods and/or covered with cheap, brittle gesso, neither of which are chopper-friendly. (Some of this junk doesn't cut well on a saw either.) So, if you are "following the rules" with your chopper, the problem is probably the moulding.
:cool: Rick
 
I moved from a Morso to a Pistorius about 7 years ago and have never regretted it. I cut mostly gessoed mouldings and could never get good cuts with the Morso, even with new blades. That all went away with the saw.
 
I agree that the chopping head might need adjusting. That last bite should be like a paper thin chop with the points of the blades just cutting through the surface. Of course if the blades are dull....
 
lois said:
I have morsol blades! My frames in my new job crumble and they never used to in my old one so i know something is up! i have my blades sharpened and its seems A LITTLE better. New job driving me crazy and it never used to be this difficult. i have doubts the are being sharpened properly... can you give me any advice!
?
Click to expand...
Not everyone is qualified to sharpen chopper blades.
If they aren't sharpened properly, they can be ruined and will never cut properly.
There is a diagram of how the blades must be sharpened and if I can pull it up, I will post it.
If metal is taken away from the wrong parts of the blades, they are ruined and nothing will make them work right.

There are some mouldings that just have to be cut with a saw.
Sometimes you can get a better cut on the chopper if you back the moulding up with strips of mat board cut to the same height as the moulding.
Keep moving the matboard with each cut so you have a fresh backing with each cut.
The matboard can give the moulding a support at the back that can sometimes give a cleaner cut.

I have had the luxury of having a chopper and a saw available.
Some mouldings just cut better on the chopper and some cut better on the saw.
Good luck and I hope this can help.
 
Like others have said choppers are great if set up correctly and the blades are good, it is definitely best to have both a saw and a chopper, space and funds can be an issue, I managed to fit both in a space I didn't think I would be able to, with a bit of rearranging, I can't pass up a bargain and purchased a cs939 at an amazing price, although I had to have the door frames took out of our studio to get it through to the workshop (wife was not a happy bunny).

Neil is spot on with the blades, for best results they should be hollow ground and not every company can get it right in fact in my experience most get it wrong, they can be re calibrated if ground incorrectly but not by normal sharpening, they have to take much more material off, one of our suppliers offers this service, not much use to you as we are UK based.

Also as some other have said some mouldings are just not suitable on a chopper, the mat card behind does help, I also found tape on the back edge where you are cutting can vastly improve the cut.


Are your blades meeting at the tips, and are they going past the back of the moulding by a fraction?
 
Every now and then I have a rummage in the shed and pull out an old stick of moulding just big enough for an odd job. Some of it must be 30 years old or more. It may be my imagination, but when ever I cut/join an olde bit it cuts like a dream. This may give credence to the idea that moulding quality has definitely gone off over the years. Environmental issues have forced manufacturers to seek alternative timbers.

Having said that there were always mouldings that were a PITA to work with. There used to be a Czech company that made very nice looking moulding, but inside it was really rough old pine. A one stick could have a finger-joint every foot. It was a challenge to cut and join, but if you did manage to cobble it together you got a good strong and very classy looking frame. It was very cheap too.

People new to the industry can sometimes have the impression that all mouldings are created equal. But some are geared to mass production and someone with a factory set-up with a big saw will cope with them. Not the same cutting on a Morso. You have to try a few and search out the friendly ones.
 
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