I have seen a number of videos where they seem to like Trend Diamond plates. (Rob Cosman and James Hamilton/Stumpy Nubbs) The plate they use is 300 on one side 1000 on the other.
On Amazon the plate alone is $114 and the kit is almost $150.
Cheaper ones were Less than thirty bucks, but reviews said they were not perfectly flat.
Before I looked at all this I used my Harbor Freight version with four sides to sharpen my planer knives. Seemed to do a good job but thought the Trend plate might be better.
I am wondering if I am over thinking this? Is the Trend plate that much better? Does it matter that much?
Yes, overthinking it. One area that HF does really well is in cheaper diamond products, if you're satisfied with the results it gives you, stick with it.
The reason you've heard of those guys is that they push product. Sometimes that is good, sometimes it isn't. When it comes to diamond plates I don't think its good.
I use a four foot level and a UV Laser....No, wait that's something else....
My planer has two blades. 733(?) Dewalt with the resharp-enable blades.
I took a piece of 2 x 4 about fifteen inches long and cut two angled grooves back to back like a V. Insert the knives so they end up with the cutting edges up and outward. The bevels will be nearly level with the cutting edges angled up a degree or two.
If you have a large diamond plate or stone and the knives are snug you could slide the edges over the sharpening surface. Mine were not snug so I just slide the diamond surface over the two knives. Easier to do than to explain. My Harbor Freight diamond thing has four sides of four different grits. I just started with the 200 and progressed through to 600 or whatever. I blackened the edge with magic marker each time. Kind of a figure 8 motion. Took less time to do it than to explain it. On the finest grit I laid the back of the knife flat on the surface and knocked off the burr and then did the bevel lightly again. Parts of the blades will slice paper.
I was wondering if the 1000 grit plate would do better.
I also have a set of the diamond impregnated film and some of them go to 14 or 16,000. Trying to figure how to use them.
Thinking of cutting a vee groove with a step on each side in the bottom and a matching stick to screw down in the middle to hold the blades and then I could turn it over and slide it on the lapping film.
My friend has a three knife planer. Thinking of cutting three parallel slots and sitting the knives in them. Might have to rearrange the knives from slot to slot to keep them even.
I ordered three or four dual-sided diamond plates up to 1200 grit from WoodTurners Wonders. I can't remember, they might be 2 or 3" wide by 8" long. He carried CBN plates in stock which made no sense to me due to the reason to use CBN didn't apply here, so he ordered diamond for me, not that expensive, had to wait a few weeks.
People are going to read this post and think, I can sharpen my planer blades and save sending them out. It took me so long to sharpen a set of 8" jointer knives that I am skeptical it is practical to sharpen jointer or planer knives this way.
The flat on a knife is so large that it is not difficult to keep it registered against the stone. The difficult part is removing several thousandths of an inch of highly abrasion resistant M2 tool steel. It has been a while since I tried sharpening jointer knives on a diamond plate (EZ lap). After tens of minutes I may have succeeded but I think I remember I gave up.
If anyone has ever bought a chisel with a dubbed over back and ground it back flat you can begin to appreciate the problem at hand. Now repeat that process on a steel whose abrasion resistance is times greater, across 36".
I have an attachment for knife sharping on a six inch grinder and have sharpened both sets of knives more than once. These knives have a thin narrow strip of tool steel laminated into softer steel. Over the years, the grinder has ground away more of the softer steel than may have been desirable, or at least not perfect. So, when I tried this, it had the effect of grinding a micro bevel on the cutting edge. This meant I was not grinding away the entire bevel. I was grinding both at the same time. I have not installed these to test them, am using the alternate set. They seemed sharp.
I am somewhat skeptical of the necessity to get these knives to any exact angle, but cutting the vee groove so its at the correct angle will get you within a degree or so.
After fiddling the the block it literally took fifteen minutes or less.
..I understand the trend to be a chinese made plate. The flatness is stated per inch, which is almost meaningless and on a razor forum that I used to frequent, several purchasers found theirs to not be flat. I'm sure they'd take them back in exchange, but for the cost, you'd expect them to actually check before sending them out.
The least expensive guaranteed flat hones (like really flat) are atoma and the DMT plastic core duos, but neither of them is probably as cheap as I recall and if you're going to do much blade sharpening, there are probably used gadgets that would assist in doing what professional shops do - blast a lot of material off.
I've touched up planer and jointer blades before, but I use both of those relatively infrequently and may be wasting my time with them. It occurred to me that I could do an incomplete job and push things along a little, but was just experimenting. For the amount of wear that power jointer blades take, you want something power sharpening.
based on what you're saying , disregard my power comment below. If they're laminated, then a diamond hone should be fine for touching them up.
comments about diamond hones still relevant, though - trend seem to be 2 to 3 times as expensive as they should be given their origin, but the entire brand is like that (mixing mineral spirits and naptha, etc, as honing plate fluid and charging a bunch for it).
The couple of times that I resharpened my blades fiddling just for fun, it was more of a clean up of the edge, and as you're saying, knowing that I was chasing it a little steeper each time.