Powermatic P60 Jointer Blades - Router Forums
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post #1 of 17 (permalink) Old 08-30-2019, 07:35 PM Thread Starter
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Default Powermatic P60 Jointer Blades

Seems the last time I jointed a few boards, some maple and poplar, everything was baby butt smooth and even. So I had some more maple I needed to joint and the edge did great but the side was horrible. The first thing I noticed after about 5-6 passes was the board was becoming a wedge. And then I noticed some ridges in the board. So I suspect the cutters, HSS, are dull and evidently have become out of alignment. Is that even possible the way they are installed? So that 5/4 maple board is not going to finish off at 1", no way. Should have checked sooner. The bearings don't sound bad and the amount of cut is light. I never do deep cuts on the jointer or planner. The fact that this 8" jointer is a 1969 model I think it's time to bite the bullet and get a Byrd Shelix head and get it on this jointer. I thought about that when I 1st bought it but......I took the cheaper rout and just replaced the blades. So rather than go down that route again I think seeing how I plan to keep the jointer just upgrade the cutter head and replace the bearings. I just don't look forward to getting the tables coplanar again.

Any thoughts?
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post #2 of 17 (permalink) Old 08-30-2019, 08:34 PM
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Co planer is for band saw wheels, isn't it. A planer requires an offset between the two table halve, with the back exactly the height of whatever cutters you install. I have a 6 inch Powermatic and looking at it, I think the movable side is running on a carefully machined rail so it stays flat (parallel with the cutter). I'm wondering if one of the blades has loosened up and is lifting the board up slightly above the raised back end. That might explain the wedge shape you described. If your blades have lasted many years, are you sure you want to replace them with the Byrd head? The way the blades are cinched in is pretty solid, but the forces acting on them have got to be pretty powerful.

I think you are describing a wedge shape looking down the end so one side is thinner than the other. If it happened all at once, I'd bet one blade moved.

That powermatic is a tank, I don't think that other than bearings, there is much else than blades behind the mis-cuts.
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post #3 of 17 (permalink) Old 08-30-2019, 09:53 PM
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I agree with Tom. My rule of thumb on a Powermatic anything is other than bearings, they do not wear out. And with your current bearings being 50 years old...
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post #4 of 17 (permalink) Old 08-30-2019, 11:32 PM
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The typical cause of "wedgies" on jointer is that the outfeed table is higher than the infeed. But since once set, the outfeed table isn't moved (unless by accident), your knives might be causing the problem. If you do decide to install a Shelix head, I would do that first, then adjust the outfeed table. You will have to adjust it anyway with the new cutter head. I installed a Shelix on my jointer a couple of years ago and really like it. You will never have to go through the pain of setting your straight knives again. I hated that, always spent hours setting the knives when all I wanted to do was cut wood.
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post #5 of 17 (permalink) Old 08-31-2019, 01:42 AM
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The knives will wear over time and as a result the outfeed table will need to be adjusted to compensate. This normally isn't much of a problem on a single pass but it gets compounded on multiple passes. And the tables do need to be coplanar just like bandsaw wheels need to be. When both tables are raised to the same level a straight edge needs to sit flush on either edge and in an X pattern.
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post #6 of 17 (permalink) Old 08-31-2019, 07:00 AM
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Quote:
The knives will wear over time and as a result the outfeed table will need to be adjusted to compensate.
Imo, the knives should be changed well before you'd need to adjust the outfield table. You never want to mess with the outfeed table, as it's the reference for the knives and infeed table.

You set the knifes to be perfectly level to the outfeed table, and the infeed table is parallel to the outfeed table.

If your jointer is cutting a taper, the knives are not aligned to the outfeed table. Or, you're technique is incorrect. With a jointer, all downward pressure should be applied over the outfeed table only.
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post #7 of 17 (permalink) Old 08-31-2019, 08:59 AM Thread Starter
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Originally Posted by Bob Adams View Post
The typical cause of "wedgies" on jointer is that the outfeed table is higher than the infeed. But since once set, the outfeed table isn't moved (unless by accident), your knives might be causing the problem. If you do decide to install a Shelix head, I would do that first, then adjust the outfeed table. You will have to adjust it anyway with the new cutter head. I installed a Shelix on my jointer a couple of years ago and really like it. You will never have to go through the pain of setting your straight knives again. I hated that, always spent hours setting the knives when all I wanted to do was cut wood.
That actually is when I decided the next time I had to do anything with the jointer it would be installing the Shelix cutter head and be done with it. As you said I don't see the table as being the issue and I did check them. The other thing that pointed at the knives was the quality of cut. I had some shallow channels in the worked surface. Of course once the board was flat the planner would take care of those but.... A good tool to set the knives is over $100 and the price of another set of knives is $60+ depending on HSS or carbide tipped $150 coming close to 1/2 the cost of the Shilex head itself. And for another $30 I can replace the bearings while it's tore down. Then when/if there's an issue it's so easy to turn/replace the helix head cutters which have 4 cutting surfaces. And only replace those that may be damaged instead of the set of blades. Cost more upfront but in the long run it will save money and time......hear that Honey? Yeah, it will be here Tuesday....I hope she likes her Anniversary gift. OK just kidding there. I'm not suicidal.......she would get something way better like a CNC machine or something Festool. Now if I could only get her interested in woodworking............

But seriously, out of all the machines in the shop I honestly think the jointer is harder to maintain and repair. Just adjusting the knives can take an afternoon and don't even think about making those infeed/outfeed table coplaner quickly unless you've done it so many times it's become routine. And then expect to take at least a few hours or more. I'll let you know when it's done.
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post #8 of 17 (permalink) Old 08-31-2019, 09:17 AM Thread Starter
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Originally Posted by Cherryville Chuck View Post
The knives will wear over time and as a result the outfeed table will need to be adjusted to compensate. This normally isn't much of a problem on a single pass but it gets compounded on multiple passes. And the tables do need to be coplanar just like bandsaw wheels need to be. When both tables are raised to the same level a straight edge needs to sit flush on either edge and in an X pattern.
Chuck,

Not challenging the post but really curious. Why would you move the outfeed table when everything else is referenced from it? The outfeed table should be the most static part of the jointer in my opinion, for what that's worth. With the knives being spring loaded and locked in the head, not to mention that they are HSS knives, the weakest point I would have to suspect is the knives themselves. I suspect they are dull and possibly misaligned.

I remember clearly the process I used to install the new knives when I bought this jointer used. The knives were nicked and dull. They chattered as they tried to cut. I bought the knives at Woodcraft, the actual Powermatic replacements which were HSS. The biggest issue I had was setting the knives height and for that I used a fairly cheap (I thought at the time) magnet jig to hold the knives in place while adjusted and tightened. Seemed to work reasonably well and the result was far better than the previous set of knives.

But I was still getting less than even cutting so I checked the tables to be coplanar with each other. Using my 5' long steel straight edge I checked the tables and found the infeed off slightly so I started the laborish process of correcting that. Several hours later the best I could do was 5/1000" off and I decided to live with that. Till now that had done well. I didn't get any woodworking done that afternoon. I tested seveal pieces of wood at least 6' long and was happy with the results until now.

I really don't see that infeed table losing its alignment but I could certainly be wrong. I learned a long time ago to never say never. I've been corrected/humbled more times than I care to admit. So while I'm checking everything including the bearings and it's tore down, it's the perfect time to replace the cutter head and give it an upgrade. My son will one day appreciate it as well.
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post #9 of 17 (permalink) Old 08-31-2019, 09:20 AM Thread Starter
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Originally Posted by ger21 View Post
Imo, the knives should be changed well before you'd need to adjust the outfield table. You never want to mess with the outfeed table, as it's the reference for the knives and infeed table.

You set the knifes to be perfectly level to the outfeed table, and the infeed table is parallel to the outfeed table.

If your jointer is cutting a taper, the knives are not aligned to the outfeed table. Or, you're technique is incorrect. With a jointer, all downward pressure should be applied over the outfeed table only.
Gerry you're echoing what I've always been taught. I agree that the outfeed table is the referenced surface and this is how I've always been told to align the tool. it's a royal PIA but necessary for good performance.
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post #10 of 17 (permalink) Old 08-31-2019, 09:28 AM
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There are a number of settings that are important but it shouldn't take that long to get the blades adjusted. First though, you need to make sure the tables are coplanar. If they are then the rest shouldn't be that complex.

The knife setting jigs that come with jointers and planers will give the right amount of blade exposure relative to the cutter head. For example, it may give a setting where 3/16" of cutter (on the face side) is exposed above the cutter head. I don't think this is critical but I do think it's good to stay in the neighborhood of where that jig says it should be.

But the knife setting jig doesn't guarantee that the knives are set coplanar to the tables because the cutter head isn't guaranteed to be coplanar unless you take the time to make sure it is and that may require time to shim under the bearing mounts to do that.

I use a flat hardwood board to set my knives by laying it on the outfeed table and letting the springs under the knives push them up against the board. (If you have jack screws that may not be a good method.) Most knife setting aftermarket jigs I've seen work the same way. If you have jack screws then maybe a magnet style jig will hold the knives in place while you make the adjustments. They may not hold carbide knives though. I don't have experience with the jack screw style heads so maybe someone else does and has a reliable method.

Even after all that it may be necessary to adjust the outfeed a few thou to get the cut perfect and there are various methods that can be searched on the web for instructions on how to tell if you need to. I disagree with Gerry that it should never be touched again once set because it may be necessary to move it to get it cutting perfectly. But after a few times of doing this you may have the knife exposure off by a bit so now you wind up going back to that setting again.

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