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Setting planer knives on Emco Rex B20

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emann

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Hello,

first post here.  During last xmas I acquired a planer model Emco Rex B-20.  The owner had passed away some months back and I got the machine with a set of blades installed and a set of spare blades. The machine works great.

Now I have some spare time, took the blades for sharpening but cannot find any way how to set the blades to ensure they are level.  I managed to find the manual which shows some form of a gauge but I am thinking that even if I find the gauge I cannot understand how I can reach the screws to tighten the blades in position as these come below the outfeed table.  Please note the attached to understand my situation - sending some pictures and page from manual with position of screws under table.

So, in view of someone with similar experience or a similar machine, do you have any hints as to how such models can be setup please.

Thanks to all.

Emann
 

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Fitzroy

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Hi Emann welcome to the site. Not sure on the specifics of your machine but video below shows how to set knives to a constant and correct height.

Planer blade setting

I use the same approach on my Wadkin using a straight piece of timber and ensuring each knife moves it a uniform amount. However, my Wadkin doesn’t have adjustment screws so I install the knives by eye, roughly even but all sitting marginally too high, and with the retaining bolts lightly fastened. I then use a pin hammer to tap the blades down a fraction at a time, checking with the wood block often.

Once all is lined up you tighten up the bolts.

Fitz.
 

emann

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Thanks to all for reply.

The video is great and I can understand the method. The only thing is that since the screw heads come below the outfeed table when the blades are top dead centre, I cannot manage to screw the blades in the final position without turning the spindle to expose more of the screw.

This fact means that many a times I end up with the blade moving slightly and hence starting all over. To get them to a decent level (if I can say so as I still get about 2mm difference on either end) it took me over an hour...so I was thinking there sure must be some other foolproof way to do it.

The outfeed table is fixed and I cannot move it to expose the screws and I think that on such machines there should be a better way of doing this knife setup...2mm is still a lot and I would need to spend more time trying to get it even more level.

Any ideas on this situation please maybe you have experience on a similar machine where screws come below outfeed table...or is it a matter of patience and trial and error then.

thanks to all.
 

Fitzroy

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The manual, link below, discusses how to set the knives. As you have discovered the process is quite annoying! I can now do it on my machines in about 20mins but that’s after some practice. It used to take much longer.

Additionally your machine is not designed for easy adjustment with no screws to adjust the blade. My Wadkin has a spring under the blade so at least your only having to control movement in one direction.

My tip would be to play with the tightness of the bolts, only tightening the ones at each end of the blade, until the blade doesn’t move of its own accord but you can adjust position with light taps of a fine hammer.

https://www.emco.or.at/index.php/do...n/hobelmaschinen/82-emco-rex-b20-english/file

Keep persevering!

Fitz.
 

emann

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Thanks for that and I had managed to find that manual.

So I have understood that it is going to be trial and error and hopefully by experience I can get to reduce the setting time.

Just to confirm, the blades have four screws. You advise to hand tighten the ones at the ends and adjust that way. Then once set i can screw in and tighten the middle ones. Or better start with the middle ones so that the ends are more free for setting up. I also noted that sometimes i can set it up quite close but when i tighten the screws and recheck it has lost alignment. So it is quite a long process. Upside to this is that the machine works fine up to now and it was pretty much free of charge.

Regards.
 

MikeJhn

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What sort of projection do you get if you push the blades all the way to the bottom of the slot, if its level with the carrier could you put a spacer underneath the blade to push the blade against and get the projection you want?

The picture above only shows three screws, where is the other one?
 

Lazurus

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Looking at the manual I would be tempted to machine access holes to get to two of the screws when fitting the blades?
 

emann

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If i leave the blades all down they drop quite far with the tip not showing from the spindle.

The fourth screw is behind the fence that is why it is not visible.
 

emann

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Lazurus":mbk76djd said:
Looking at the manual I would be tempted to machine access holes to get to two of the screws when fitting the blades?
you mean machine holes in the outfeed table directly above the screws? wouldn't that affect the wood going out on the table when planing if in case the edge of the woods gets caught in the hole?
 

Fitzroy

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I would use the end not the middle, the middle will act like a pivot, if you knock one end down the other will pivot up. Yes once adjusted, tighten everything thing up.

The blades moving on tightening sounds very annoying and rather like a design weakness. I can see the securing bolts go through the planer knives, I can only guess the knives are contacting the screws at the edges of the elongated holes and thus moving the knives when the bolts rotate?

Fitz
 

emann

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the ebay ones I managed to try a set before getting the machine to my garage...but in view of screws becoming under the outfeed table they are of no use as when the magnet holds the knife at top dead centre I cannot access the screws unfortunately.
 

Fitzroy

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I needed to change my planer knives so took some pictures and a few videos in case they help.

I have a Wadkin BFT9 which uses leaf springs in the cutter head to hold up the knives and chip breaker.

With the knives and chip breaker removed you can see the springs in the channels.
7D79A1C1-8B4C-49B9-A13D-1EC56B4B0A94.jpeg


The new knives and chip breaker are placed into the channel, I love the reference letters on the chip breaker so you can’t put the back wrong.
8DCB0538-79B5-4510-9AF2-FF1499360ABC.jpeg


The new knives are a pretty sharp so I push them down against the spring with a block of wood. The infeed table is lowered as far as possible so I can just get an Allen key on the end retaining bolts which I nip up a tiny bit.
E215113B-24CD-4F6A-801B-D1A5DEF90F33.jpeg


I took the block away and it was obvious the knives were far too high so I used the block to push them in to a more reasonable start point for finer adjustment. Your challenge is that you don’t have a spring pushing back. My solution would be to use a magnet to hold them roughly whilst you nip the retaining bolt up.

With the knives roughly set I could use the ruler trick to see how bad the set was. The knives are way too high and the wood block is being lifted and moved c. 20mm rather than the desired 5mm.
Knives too high.

I then use a pin hammer to tap lightly on the knife behind the edge, you can see the blade moving back incrementally. You’re aiming for an equal projection on each side, you then repeat the ruler trick and gradually fine tune each side until you get a 5mm movement of the ruler.
Tapping the knives back.

On the first try videoed above I tapped the knife back too far, there was no ruler movement as the knife didn’t contact it. So I had to slack off the bolts let the knife rise and start again. Second time around I took two or three adjustments to slowly move the knives back. Don’t hit the edge of the knife with the hammer!

Correct knife setting

The knife advances the wood about 5mm on each side, the far side is a fraction lower but I was happy.

Hope that helps.

Fitz.
 

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emann

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This is really of help Fitz and greatly appreciate the time you took to shoot the video.

I have basically done the same thing to set them up and without the spring it takes a significant length of time...and patience.

I managed about a 2mm difference in movement of vertical line on the wood. I just cannot achieve anything better than this. When I use the planer I try to rotate the wood clockwise on each pass so as to minimise the difference in thickness from one end to the other. I can manage with this but in as far as this old machine still is a beauty and great to work with, definitely setting up the blades is no joke and a faulty design.

You think some form of springs at the bottom beneath the knives will help in some way?

Thanks once more.

Emann
 

Fitzroy

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I think a 2mm difference in the amount the wood moves is close enough, I think that’s about what I ended up with. On a 55mm diameter cutter block that 2mm difference equates to the knives taking a 0.055mm (2 thou inch) thicker cut at one end than the other. Which is not an issue in my book.

The maths also shows the smaller the diameter cutting block the harder it’ll be to set the blades to make a similar movement. Your machines 55mm cutter block and is slim for any machine so you’ve done well!

Fitz.
 

MikeJhn

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Fitzroy you ought to use the plate glass method, setting the blades would take all of two minutes.

To the OP just a thought can you get to the locking screws from below the outfeed table above the thickness bed?
 

emann

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Thanks MikeJhn for your input. Unfortunately the screws are not reachable either as I just cheked...the head of the screws remains barely visible from underneath the outfeed table with the blades at top dead centre...I really wonder how no thought was given to this or else I am not getting this design at all.

Can you elaborate a bit more on your glass method please.
 
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