Delta planer depth setting

[tedrussell]

I work in a community workshop (makerspace), and just set the blades on a Delta RC-33 (I'm pretty sure that's the model number) 13" planer. 

Sort of long story: It was not planing well, and a machine repair expert set the blades. The next day, one of our users was planing, and said the machine went 'haywire'. (I'm suspicious of the particular user - longer story there.) Two of the blades had come loose. The repair guy couldn't come back for health reasons, but let us borrow the jig, and two of us set the blades, tightening them really well, and the planer is now operating properly.

Before returning the jig, and concerned about the repair guy's availability, I measured the key dimensions, in particular the height of the step between where it sits on the 3"-diameter head, and where it contacts the knife edge. I took a feeler gauge, and the step height is about 0.020" +/-0.002". In other forums, for this planer, I've found bigger numbers, ranging from 0.035" to 0.060" for the knife height above the head. Can anyone explain the discrepancy?

I've attached two photos of the jig.

[tablesawtom]

I believe the cutting edge of the blade rests against the pin. The pin orientates the blade in relation to the blade rotation because the blade is at an angle in the head so that the cutter will have a shear angle  For instance on a hand plane the shear angle is 45 degrees. Everything that a person grinds away is only the relief angle. 

 The springs under the blade raises the blades up against the top of you setting gauge thus establishing the cutting edge in relation to the cutter head. The importance of this is, if the cutting edge is to high or to low it effects the setting of the pressure and feed rollers. To high and the outfeed roller will not grab properly and to low and the knives will not take out the marks from the spiral infeed roller.

The real problem with that planner is the blades will move as the gibes are tightened, The twisting action of the screws will overcome the springs pressure and the knives can go out of level with the head..

The one thing I feel is the most important is you datum  ( a datum is a surface, line, plain or feature assumed to be prefect  it doesn't have a tolerance but everything is referenced from it.) Is the bed of the machine and not the cutter head. So board thickness id determined by the distance the cutting edge is from the planner bed.  if the cutting edge is at an angle then there will be different thicknesses from one side to the other. If one blade is closser the the bed than the others then one blade will do all the work and when it is dull the planner will stop working  and you will get garbage out of it. 

Even if the knives are prefect to the cutter head, my question is: what if the cutter head is out of parallel with the bed of the machine.

Anyway I have this machine and I use this tool and I rough set the knives I try to set all three knives within .002 total indicator runout  and then I the other side until all the cutters are parallel to the bed and within .002 indicator run out.

That way all three knives take the same amount off on every cut and I can send a 2 inch wide piece through on one side and a 2 inch wide piece through on the other side and they will be the same thickness. It is my go to planner and I only put in fresh blades  one a year or year and a half.

This is what I use.

   

Tom

[tedrussell]

I believe the cutting edge of the blade rests against the pin. The pin orientates the blade in relation to the blade rotation because the blade is at an angle in the head so that the cutter will have a shear angle  For instance on a hand plane the shear angle is 45 degrees. Everything that a person grinds away is only the relief angle. 

 The springs under the blade raises the blades up against the top of you setting gauge thus establishing the cutting edge in relation to the cutter head. The importance of this is, if the cutting edge is to high or to low it effects the setting of the pressure and feed rollers. To high and the outfeed roller will not grab properly and to low and the knives will not take out the marks from the spiral infeed roller.

The real problem with that planner is the blades will move as the gibes are tightened, The twisting action of the screws will overcome the springs pressure and the knives can go out of level with the head..

The one thing I feel is the most important is you datum  ( a datum is a surface, line, plain or feature assumed to be prefect  it doesn't have a tolerance but everything is referenced from it.) Is the bed of the machine and not the cutter head. So board thickness id determined by the distance the cutting edge is from the planner bed.  if the cutting edge is at an angle then there will be different thicknesses from one side to the other. If one blade is closser the the bed than the others then one blade will do all the work and when it is dull the planner will stop working  and you will get garbage out of it. 

Even if the knives are prefect to the cutter head, my question is: what if the cutter head is out of parallel with the bed of the machine.

Anyway I have this machine and I use this tool and I rough set the knives I try to set all three knives within .002 total indicator runout  and then I the other side until all the cutters are parallel to the bed and within .002 indicator run out.

That way all three knives take the same amount off on every cut and I can send a 2 inch wide piece through on one side and a 2 inch wide piece through on the other side and they will be the same thickness. It is my go to planner and I only put in fresh blades  one a year or year and a half.

This is what I use.



Tom

Thanks, Tom. Our planer has no issue with thickness variation across a board. The question I have is best illustrated by the attached sketch, which shows the blade height above the cylinder of the cutter head. The jig we used sets this height to 0.020", but other sources have bigger numbers. It's really just a curiosity question, because the planer is working fine now.

[tablesawtom]

.02 in not a lot of height from the cutter head I will check mine tomorrow and get back to you.

Tom

[tedrussell]

.02 in not a lot of height from the cutter head I will check mine tomorrow and get back to you.

Tom

From what I've read, it seems pretty small, but that's the step height on the jig from my measurement with the feeler gauge. I'll be interested what measurement you come up with.