JOINTER CUTTER HEADS.

[DSEL74]

I'm a bit annoyed that my jointer turned up with a different cutter head in it than it was made with.

The original is a round safety head which has four blades
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What has been put into the machine is a round head also, but it only has two blades.

Now I'm fairly sure what the answer will be and I am sure it will annoy me further but,…….Will a four blade cutter give a better finish than a two blade??

[Kuffy]

In order to have a better finish from multiple knives, the knives must be set at the EXACT same height in the head. Big 4 sided moulders have attachments which run what is basically a piece of chalk across the cutterhead while it is spinning, effectively knocking the the cutting edges down so that all 4 blades are at the same height (this is called jointing the knives).

Since your jointer will only have manually set/adjusted knives in it, only one of those 2 or 4 knives will sit higher than all others, and it is this knife that will do the majority of the work. After running for some time, you can take the knives out and you will clearly be able to feel that the higher blade is most blunt. You can also see/feel the difference between cutter heights when setting the knives at the outfeed table height by using a straightedge, one cutter will slightly touch the straightedge, while the other cutters completly miss (not by much, 0.005mm maybe)

In short, unless you are planning on racing the timber over the jointer at a rapid rate of knots (im thinking off the top of my head...about 17 meters/min, which is stupidly quick for any real accurate work) you will see absolutely no benefit to having more than 2 knives...in theory u only need one knife, the other knife is just there as a counterbalance. 4 knives just makes it harder to balance the head and more expensive when sharpening, and more time consuming when setting the knives.

[artful bodger]

Hi DSEL74
I'd be annoyed as well if the machine did not have what it was supposed to have installed when you got it. If it was brand new I'd take it back.
Guessing it's second hand?
Also guessing you may have opened a wee can O worms here regarding number of blades.
Kuffy reckons 2 is fine, in fact says one will do the job if it weren't for balancing.
Why then do you think some manufacturers make 3 and 4 blade machines?
I used to have a 2 blade planer but cut it up into bits with a big angle grinder and threw it out cause the tables were out of whack. not because it had 2 blades. Then got a 3 blade one which I'm happy with. Setting the 3 blades is harder than setting 2, but I reckon I get one third more distance between sharpening with three rather than two. If you could set the blades perfectly the same(which I can't) then surely they would share the wear. My thicknesser has 4 blades and I am happy with it, springloaded blades makes it a treat to set the blades. Wouldn't swap it for a 1.2 or 3 blade machine for quids.
Having said all this though, I feel a bit "old school" as I've heard about spiral head cutters and have not even bothered to find out more about them.

[DSEL74]

Yep it is second hand, well possibly more hands, made 1912. In the US of A. and I bought it online from Adelaide and had it delivered here.


However I asked a lot of questions including, modifications, damage, repair etc. it was said to be original.

[artful bodger]

Well then, I suppose the best you can do is get the blades the sharpest you can.
Set them up in the cutterblock as accurately as you can. (there are good tips as how to do this,available on this here forum) and just enjoy your new machine. Beats a hand plane any day of the week fyarsk me!.

[DaveTTC]

The guy who owned it had died so I think you were dealing with the grandaughter and I met the daughter. So they likely did not have any real idea.

As for the blade ... Not original but I would look at a spiral cutter.


Dave the turning cowboy

turning wood into art

[DSEL74]

Spiral cutter is way out of my reach $$$ wise. I probably just going to live with it as is.
I have no hard feelings against the seller, just annoyed at the situation because I have heard the original set up was excellent. I also wondering why it has been changed out???

[Sir Stinkalot]

The good news is that there is plenty of good information available. I would highly recommend posting the machine on http://vintagemachinery.org/mfgindex/detail.aspx?id=224 to help keep the history alive. This one is almost the brother http://vintagemachinery.org/registry...l.aspx?id=2920 only 40 numbers different in the serial number.

I agree with Dave .... I don't think the sellers would have known too much about the machine. They mentioned that it has been around and used by the father / grandfather for many years but if it was built in the early 1900's I doubt that he would have been the first buyer and it may have been modified before he got it.

My 12" has two blades in a similar cutter head. I didn't inspect your cutter head too hard but I think it was very similar. I find the two blades to be sufficient and certainly wouldn't be too keen trying to get four set at the same height.

If I used mine more I would seriously look at a spiral cutter head, then faint at the price and remember how happy I am with two blades. It could be argued that adding a spiral head is going against the machines history but at the end of the day I would rather see an old machine still getting used to the best of its abilities.

[DaveTTC]

Bushmiller has a special grinder set up for doing long blades. If you had a spare set he might sharpen them for you. Not sure where or how much to get it done by a pro


Dave the turning cowboy

turning wood into art

[DSEL74]

The machine is already up on OWWM and Vintage machines, they have helped me with the correct dating of the machine.

The seller said the Grandfather had the machine since new, but I doubt that, maybe had it ever since the Dad could remember maybe.


I don't have a spare set of blades at this time, and I haven't had them out to see how much meat is left on them. They are as blunt as buggery though and will need sharpening. I will also have to look into getting a new/another set of spare blades. Unfortunately other than the blades in it I don't have any specs to go off.


If the thicknesser is anything to go off the 600mm spiral head was quoted at $5k

[DaveTTC]

I reckon you could get it half that

The jointer would be a 300mm blade?

At a guess I would think maybe $1500 for the jointer .... Still a lot more than the jointer cost.


Dave the turning cowboy

turning wood into art

[DSEL74]

http://mywoodcutters.com/SHELIX-head...2_inch_Jointer

Still can't afford that.

[pjt]

Now I'm fairly sure what the answer will be and I am sure it will annoy me further but,…….Will a four blade cutter give a better finish than a two blade??

Yes and no or no and yes, maybe , it depends!

If we assume that all the blades are sharp, same height and set paralell with the tables, then if we say a rough finish has a pitch of 6+mm, a medium finish has a pitch of 3 to 6mm and a fine finish has a pitch of 0.5 to 3mm.

The pitch is a function of no. of blades, speed of rotation of cutter head and feed rate of board across cutter head, so for a given machine number of blades is fixed as is the speed of cutter rotation, most often the variable is the feed rate of the board, (excluding a feeder), a fast feed rate will give a rough finish, a slow feed rate will give a fine finish.

If we now say the feed rate is fixed but we can swap from a 2 blade to a four blade setup it follows that a 2 blade will tend to give a rough finish and a 4 blade will give a finer finish.




Pete