I was having lunch with a business acquaintance. We were talking about various issues that he saw in sawmills and during that conversation he said, “Did you know that many sawmills that I’ve visited have had to open up the gap between the sawguide and the sawblade, in order for the sawmill edger to start?”
I began to wonder about the scope of this issue, so I asked him how much of a gap that these mills are running. He said he’d seen up to 0.005” and had heard of some that had up to 0.007”.
I was shocked!
That was almost five times the recommended industry standard of 0.0015”. I asked if these mills had issues holding lumber sizes. He responded that the mills using the higher gap were having many issues in keeping consistent lumber sizes, and experienced more downtime than mills using the proper gap between the sawblade, and the sawguide. My acquaintance told me that because of the size issues and downtime that these mills were having problems with productivity, and were only making a fraction of the money that the mill could make if these issues were resolved.
Of course I asked him how the sawguides in the mill looked. His answer was abrupt. “Terrible and really beaten up.” He also added that many of the sawguides that looked new were all over the place in terms of accuracy which indicated they may have been poorly made. He then added that he was concerned for these mills. He used the words “They look like they are in trouble!”
Unfortunately I have heard a lot about this issue in the past, and sadly I think that I will hear about it again in the future. The issue lies in gap control. It’s important to maintain the gap between the sawguide and the sawblade at 0.0015” because any more of a gap within board deviation will then start to climb rapidly. An increased gap contributes to a decrease in the accuracy of the lumber and causes size control problems further down the line at the kiln and planer.
The problems occurs when the sawguides are in poor shape or inaccurate, as it’s difficult to keep the gap between the sawguide and sawblade to the recommend 0.0015”. This leads to the sawguides binding up the saws and makes it difficult to start up the sawmill edger. The sawblades and sawguides are acting like tight brake discs and pads which prevents the motors from turning the saws. Many mills resort to increasing the gap to avoid this binding in order to get the sawmill edger to run. This then leads to all sorts of problems as I described above.
I would highly recommend having a good look at your sawguides and their accuracy. Sawguides that are in poor shape or inaccurate will lead to real problems in gap control and make the sawmill run poorly. See if you are running to a gap larger than the standard of 0.0015”. Controlling the gap between the sawblade and the sawguides will definitely contribute to an increased output of good quality lumber, and decrease the downtime of your sawmill.
Author: Udo Jahn
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