Cutting Down Planer Blades

[Homer Faucett]

I've used a Ryobi AP-12 thickness planer for the last 10 years, and have been limping along with the original set of blades. They actually perform quite well, but I've planed a lot of oak, as well as some rough cherry and maple, and the blades have seen better days. So, when I checked into getting a new set of blades to switch out while the old ones get sharpened, I noticed that Ryobi does not make replacements anymore, and only a few people on the face of the earth seem to carry them . . . for about $70 a pop. So, I've continued to soldier on with the old ones.

Fast forward to a few weeks ago, when I picked up a few of the Hitachi planer blades when Lowe's put them on clearance for $6. As I compared the Ryobi blades to the Hitachis, the indexing holes are in different spots (a good thing, if you ask me), but the width and thickness of the blades are identical. However, the Hitachi blades are about 1.5" longer than the Ryobi.

Now, I'm not a metalworking guru, but I do have a few tools like a bench grinder and an angle grinder with a cutoff wheel. I understand that you can ruin the temper on planer blades if you go crazy, but is there any reason why I can't just use my cutoff wheel in a patient manner to cut these down to the right size, and then square them off on my bench grinder? It seems to me that with some patience on the grinders (maybe with some water spritzed occasionally, and a steady hand at the drill press to drill out a few new indexing hles, there is no reason why I should not be able to retrofit these.

Does anyone see a flaw in this plan, or have any tips?

[Rick Levine]

I'm far from an expert in this matter but since the blades rotate at a high rate I'd be worried about the balance of the blades after you cut them down. I would think vibration, if they are out of balance, if that even matters, would tend to loosen the bolts after a while. I hope others with more experience and knowledge will respond.

[CPeter James]

Time for a new planer. The risk that one of those blades might come out of the planer and kill or injure you or someone else is not worth it. There are some good deals out there on current production lunch box planers or maybe this is the time to move up. You mentioned that the indexing holes are in different locations. That would mean that you could not properly locate the blades, further increasing the risk of a problem.

CPeter

[Bruce Page]

Hi Homer,
Good news & bad news…
Sure you could cut the blades with an abrasive cutoff saw but unless you did it underwater or under a heavy flood of water, you will not be able to keep it cool enough to retain the temper.
Now for the bad news, I’m not sure what the Rc hardness of a planer blade is but they are very hard. You will not be able to drill it on your DP.

[Gary Keedwell]

Hi Homer,
Good news & bad news…
Sure you could cut the blades with an abrasive cutoff saw but unless you did it underwater or under a heavy flood of water, you will not be able to keep it cool enough to retain the temper.
Now for the bad news, I’m not sure what the Rc hardness of a planer blade is but they are very hard. You will not be able to drill it on your DP.

I agree with Bruce about the abrasive cut-off. It can be done with alot of water. If you invest in a carbide drill and are very careful, you could possibly drill the holes. IMNSHO

Gary K.

[Dick Strauss]

Homer,
You could cut the blades with an angle grinder w/metal cutoff wheel. If you try this, make sure you cut it 1/4-1/2" long so that you can grind away the portion that has lost the right temper/hardness very slowly.

I agree with others about drilling HSS. It will take a cobalt or carbide bit to drill the new holes easily. DAMHIKT:D

Good luck,
Dick

[larry fredric]

You might try E-bay!

[Scott Whiting]

Cutting to length is no problem. They are hardened steel and laminated on top of that. The cost of drilling new holes exceeds the cost of those $70 knives you backed away from. At this point buy a new planer or shell out for the backup set of knives.

[Bruce Page]

If you invest in a carbide drill and are very careful, you could possibly drill the holes. IMNSHO

Gary K.

Possibly….using a milling machine and a rigid setup and a high quality carbide drill or endmill – no masonry bits from HD. You aren’t going to get there with a consumer grade drill press, they simply are not rigid enough.
IMHO :)

[Gary Keedwell]

Possibly….using a milling machine and a rigid setup and a high quality carbide drill or endmill – no masonry bits from HD. You aren’t going to get there with a consumer grade drill press, they simply are not rigid enough.
IMHO :)
Yea Bruce...Sometimes the machinist in me forgets .......:rolleyes: :)

Gary

[Chuck Wintle]

Busy Bee Tools has the exact blades for the AP12 at $45, however I don't know if they ship to the US.
http://busybeetools.ca/cgi-bin/product10?&NMCLASS=00112&NSBCLASS=00134&NETID=1820580825071534315

[Kermit Hodges]

Just cut down a set of jointer blades with a cut off wheel no problem. Did not overheat them either.

[Cliff Rohrabacher]

The only way to drill hardened High Speed Steel is with a grinding head or diamond compound on a copper shaft end or an old school plunge type EDM machine. The first two will take forever. The latter is likely out of the hobbyist's league - but you can build one yourself if you want to take the time and effort.

Cutting Hardened HSS is less an issue. The stuff has excellent cherry red hardness. Which is the Trade's way of saying you can get it red hot and it still won't distemper.

Hardening High Speed Steel is done in molten salt baths, diamond-block, and reducing atmospheres. It is very tough stuff.

[Homer Faucett]

Thanks for the input. It sounds like cutting them down should not be a problem. I don't know how cutting blades down length-wise could cause an imbalance, particularly if both blades are cut down to exactly the same length.

I suspected that drilling would be the tricky part, but thought that it might be doable with a carbide bit. It sounds like it's not advisable with a drill press, though, which surprises me somewhat. I may check around, as I have a friend with a mill who does gunsmithing. While it will be important to drill the index holes in the right place, it shouldn't be rocket science to put 2 holes in each blade along the center line. I find it hard to believe that it would normally cost more than $70 to drill 4 holes, but I learn something new every day.

I'll be upgrading to a floor planer in the near future, but I will keep this planer until it dies. It seems strange to me that there is so much conflicting information about distempering steel, and the ability to cut down hardened HSS planer or jointer blades. My impression was that this gets done quite often by guys with old machines. For $6, I'm sure not out much if I ruin the blades. Regardless, I can still sharpen the old ones that came with my machine, as they are still in pretty good shape. It seems pretty silly to buy a new machine when you can just get the old ones sharpened.

[Dave Sabo]

Homer, the blades for the AP12 cannot be sharpened. Well I guess any thing is possible , but they wern't designed to be sharpened, and knowing how thin and narrow they are, you'll likeky have alignment issues. I know 70 buck for that bit of steel looks outrageous, but look at it like the cost of your hobby. Golf balls are expensive and you loose those, if you are a boater, filling up the tank is big $$$$ and you don't have anything left at the end of the day. At least with the outrageous knives you have a paperweight.

[Rick Whitehead]

Homer,
I had the same problem you do.I bought a used AP12 awhile back, and needed blades.I checked with Ryobi, and thought Ryobi's price was outrageous.Their website proved difficult to use also.
What I ended up doing was buying a set of Ryobi blades off eBay. I think I paid about $35.00,which was still high, but a LOT less than Ryobi.I also went to Sears and looked for a set of blades,
since they used to sell a planer much like the AP12. I didn't find an exact match, but I did find that the #9_29459 blades had the same width and hole spacing. They were 13 inch blades, but I can grind them to the length of the original Ryobi ones.I think they were about $30.00.
I'm told that the Delta 22-562 blades for their planer will fit the Ryobi without modification.
My sharpening shop told me that they could resharpen disposable planer blades, but that it would cause problems with some planers because the knife wouldn't project far enough from the cutterhead after sharpening.I looked at my planer, and the knives project about 1/8", which would still leaves plenty of room after resharpening. You might try having your knives resharpened, if they can be done cheaply enough to warrant it.
As far as cutting them down, I plan to use a cut-off wheel in an angle grinder to cut them off,and then clamp them together and grind to final length with a bench grinder. I will have to cut off both ends because of the hole spacing.Since they will end up the same length, they should be balanced. Even if they do end up slightly out of balance, it shouldn't be a problem. It might wear the bearings out faster, but it won't present a safety hazard, since the knives will still be securely fastened in the head.
Hope this helps.

Rick W