Author Topic: Wood Burning on Crosscuts  (Read 1168 times)

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Offline Mike Goetzke

  • Posts: 294
Wood Burning on Crosscuts
« on: May 20, 2019, 10:41 AM »
I bought some fence planks at HD for an outdoor project. They are called Alta Premium treated - think they are hemfir/spruce.

When crosscutting I'm getting a little burning like you get with a dull blade. I could feel more resistance as the blade was fully engaged in the middle of the board. This is a new Makita cordless with not much mileage on the blade (although I did just finish several cuts on some MDF). I did try to measure the toe-in. This is difficult but results did show recommended value. I found the saw was little loose on the track so I adjusted that and only made couple cut but seemed better.

So, I'm thinking the burn is most likely dull blade, bad toe-in, or loose fit on the track. Any experience to help me diagnose this appreciated.

Thanks
Mike

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Offline Michael Kellough

  • Posts: 4109
Re: Wood Burning on Crosscuts
« Reply #1 on: May 20, 2019, 11:36 AM »
Is the saw on a guide rail?

Is the blade thin kerf with minimal set?

Is the burning on one side of the blade or both?
If only one side it’s more likely toe adjustment, unless the saw is used freehand.

Offline Peter_C

  • Posts: 779
Re: Wood Burning on Crosscuts
« Reply #2 on: May 20, 2019, 02:44 PM »
Could be the board twisting as you release the tension. Are they cupped at all? Treated wood is famous for twisting as it dries.

A blade with fewer teeth would probably help.

Make sure you are maintaining the same pressure on the saw all the way across so angles are not changed in the middle of the cut. Two hands on the saw is good, but the rail needs to not pivot either.

*shrugs* I'd be using a 6.5" cordless framing saw with a carpenters square, just don't breathe the dust. An HKC with a cross cut rail or Mafell might be in order someday for both of us.

Offline Mike Goetzke

  • Posts: 294
Re: Wood Burning on Crosscuts
« Reply #3 on: July 08, 2019, 09:39 AM »
I'm working another project and getting burning on some cuts. The wood is coffee bean tree - have never used this before. The wood seems to have more internal stress than others I've worked with. The burning is at the end of the cut on both sides. Just for grins I made a few cuts on some ash I had laying around and no burning.

Is this do to internal stress?

Thanks,
Mike

Online Cheese

  • Posts: 6268
Re: Wood Burning on Crosscuts
« Reply #4 on: July 08, 2019, 11:02 AM »
It's probably just a very dense wood, you can tell by its heft. I get that same burning on Jatoba (Brazilian Cherry) cross cuts & miters. The Janka hardness rating on Jatoba is 2700, while ash is around 1200 and maple 900.

All of the South American hardwoods (which I'm assuming coffee bean would be part of) fall into the 2000-3600 range.

Offline Jiggy Joiner

  • Posts: 698
Re: Wood Burning on Crosscuts
« Reply #5 on: July 08, 2019, 11:26 AM »
The main causes of timber burning when cutting, is usually due to the blade being blunt, or being dirty with a build up of resin etc. Also putting a spinning blade through timber too slowly can often cause burning. Depending on the type of saw, cutting in a series of passes instead of one cut, especially in thicker stock can help a lot.

The density of the wood can also cause issues, I have some Brazilian mahogany here that is very heavy, and resembles machined steel! This stuff really is dense, I think it would last a lifetime, and then some! I am sort of dreading putting it the through the planer, and cutting it.
I worked a lot with Brazilian hardwood about thirty years back, and it blunted everything it came in contact with!

Offline kcufstoidi

  • Posts: 826
Re: Wood Burning on Crosscuts
« Reply #6 on: July 08, 2019, 12:23 PM »
Looks like your cutting Kentucky Coffee Tree. Its medium hardness coming in at 1390 on the Janka hardness scale. Take a look at the link. Some woods have a tendency to burn a little more especially with a blade that is borderline sharp/dull.

https://www.wood-database.com/coffeetree/