Jointing knives of a side-head planer

Choosing and using the proper stone when jointing knives used in a side-head planer. November 7, 2000

We are currently running a Yates A20 planer 1962-66 with belt driven side heads. The heads are the 10 knife LVL model by BGR. What is the best way to joint these knives & what type of stone should I use?

The type of tool steel and the spindle speed will determine the type of jointing stone. Also the accuracy of the grind must be known.

There are two types of jointing stones used today. They are the hard and soft stone styles. The soft stone works well for high rpm machines with accurate ground tooling. The hard stones work with tools that are hand ground and less accurate.

The stone must be shaped to fit into the tool. This shaping must be done before the stone is put into the holding bracket. The stone is then chipped in with the head and then pushed into the head while the head is at operational speed. This causes the removal of some metal off of each knive. This removal puts all the knives into the same cutting circle. Sparks can be created while doing this with both the hard and normal soft stones. There is a new non-sparking stone available from MSI that reduces the risk of fire. You can contact them at 704/528-3513.

Dave Rankin, forum technical advisor

From the original questioner:
How do you shape your stone to start with? Our sideheads run at 4200RPM and we grind the knives on a Reform flat bed grinder. The knives are initially set up on a stand and shaft assembly in combination with a dial indicator. We check both the radius & position of the side of the knife at this time. Any further suggestions?

In the MSI catalog there is a description on how to select and how to use jointing stones. This is a preveiw of usage. Also in "The Profiler", the Grinderman's Association newsletter additional information discusses the use of jointing stones. The Grinderman's can be reached at 704/528-3539.

Dave Rankin, forum technical advisor

From the original questioner:
We are running an early 60's Yates A20 Planer with belt driven side heads spinning at 4200 rpm. The right head sticks when we are trying to adjust for profiles. Upon investigation we found that this side runs 28-35 degrees warmer than the other side. We've changed bearings top and bottom, cleaned and polished all housings where they mate together, run grease recommended by Yates, all to no avail. Has anybody else had this problem and what did you do?

Sticking of the adjustment usually indicates a build up of contamination. This occurs frequently. The only way to properly repair this is to take the system apart and clean up the slides. As for the temperature difference, this may be due to the motor pull. If this cutter is removing more material it will heat up more. It could also be the bearings or the lubricant. There are many new lubricants that are available. I use Tech's Choice grease. This grease is fortified with additives that become part of the metal bearing race. It provides the metal with a great reduction in heat.

Dave Rankin, forum technical advisor