Setting high speed knives on any jointer

[Tom Bussey]

I first started to reply to another post on the topic, then I though better of it and I will respond on how to and to what doesn't work even though you think it does. My qualification for writing this is I served a 4 year apprenticeship ( 55 hours a week) as a Tool and Die Maker. I worked 60 years in the trade and I am still working 15 hours a week. And also in that time I managed to also serve a 4 year apprentice in Mold making, and for 3 of the four years I was a lead mold maker or the projects. And secondly if you have an inserted cutter head, they have nothing in common with what I am writing.


First things first. The out feed table is your Datum, and the cutter head may or may not be co-planner with the out feed table. A Datum is a line, plane, surface or feature assumed to be prefect. It does not carry a tolerance but every is referenced from it. Manufactures do a great job getting a cutter head co- planner with the outfeed table, but it still depends on who located the parts, what day it was machined or even what time of day it was machined as well as how accurate the machine that machined it. In other words you will be very lucky to have one that is prefect.

And feeler gauges suck when measuring anything. But if it is all you have it is at least in the right direction. Also magnates do not work and if you think so you have been sold a bill of goods. There are some that set on the cutter head and where does it leave you if the cutter head is not co-planner with the out feed table. Then there are some that set on the out feed table and the knives are held in place in the cutter head. Which is a great starting place. The problem is as the knives are tightened down with screws and there is rotation of the screw when tightened causing the knife to usually rise a little when tightening. As was mentioned on a reply on the other post. If you tighten it down tight and then move on the shift is greater than just snugging it down and then torqueing down in stages. Because of the twisting of the screw the magnet can not hold the knife in place.

Now if your cutter head has jacking screws you are very fortunate. Mind does not. If you do snug down the two out side screws and then raise the knives a little until all are set at the same height and tighten

The tool I am going to show fixes the problem. It is placed on the outfeed table and it will read the high point of the blade as it is rotated under it. The indicator point is a 1/2 diameter flat so you can rock it back and forth to get a reading. The out feed placement has no bearing on what is next. Rotate the cutter head and try to make it so all thee knives are at the same setting I prefer to rotate the dial to zero. it is an easy number to remember. Do not assume anything go back and recheck the other side. Tighten a little and repeat the process over until fully tightened. I adjust the knives so that the total difference is no more than .002 Don't try to get to prefect at first it will come in stages.

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Next set the gauge to zero while it is on the outfeed table and then slide it over the cutter head and raise or lower the outfeed table so it is zero. Now the out feed table is exactly the same height as the knives and all three knives will take exactly the same depth of cut. and then move it over the infeed table to set the depth of cut you want. I prefer to set my table at .0156 which is 1 /64TH 2passes is equal to 1/32 and 4 is equal to 1 /16 I prefer 4 light passes to one 1/16th pass and I can do a 8 inch wide board the length of my table and then some with one hand.

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[Ron Citerone]

Tom, that was an awesome post! I wish I knew that stuff years ago when I had to switch out straight jointer blades on several jointers. Luckily now I belong to a shop with carbide cutter bits that are set by an very experienced crew. I love the no nonsense approach you shared right there!

When someone with your training and experience posts I listen. Others should also.

[Cameron Wood]

Good info., thanks!

[Andrew Hughes]

Curious Tom why don’t you use a button tip? Then you can roll the head backwards and indicate the knives without moving the holder. Once the top dead center is found. The button tips I have have a small flat that’s plenty big for a knife edge.
I set all the knives as close as possible out of the head. The outfeed is set by letting the cut determine the height.

[Kevin Jenness]

Good advice about sneaking up on tightening the gib screws and rechecking as you go. Like yours, Tom, my jointer lacks jack screws so I have plenty of experience at prying and pushing the knives into line. Since I went to carbide tipped I do it less than once a year which is fine with me. I use a straight edge resting on the outfeed and watch the "carry" distance that the rotating knives pull it along to gauge knife height, then adjust the outfeed table according to the cut.

[Joe Calhoon]

I set manually for years on my SCM cast iron J/P.
One thing I found helpful was wiping a light coat of oil between the knife and gib. This helped keep movement to a minimum while tightening. That machine had a setting jig that rested on the jointer table that did not work great. Ended up buying a dial indicator for planer heads from woodworkers tool works. Then setting the out feed table to the head with a well planed hardwood piece to get 3mm movement.

[Brian Runau]

I first started to reply to another post on the topic, then I though better of it and I will respond on how to and to what doesn't work even though you think it does. My qualification for writing this is I served a 4 year apprenticeship ( 55 hours a week) as a Tool and Die Maker. I worked 60 years in the trade and I am still working 15 hours a week. And also in that time I managed to also serve a 4 year apprentice in Mold making, and for 3 of the four years I was a lead mold maker or the projects. And secondly if you have an inserted cutter head, they have nothing in common with what I am writing.

Tom:

Not being a machinist, just a woodworking guy, but a technical sales background I have a couple questions. Is there a source for the tool you show in your pictures? .002 you mention is that the final tolerance in height across each blade from one side to the other?

Thanks. Brian

[Tom Bussey]

I believe it was called a One Way Gauge and Wood Craft sold it. I am not a good searcher so I do not know if they still do. Andrew, The point came with the gauge. But I love the tip which can be gotten from MSC. The body can be made out of wood, but the weight is very nice and the hole for the indicator needs to be as perpendicular as possible. Since it is a direct reading indicator you will have a cosign error if it is not perfectly, in this case, perpendicular. if used on other applications watch your accesses. When using it for a short travel situation the cosign error isn't enough to make a difference but a full 1 inch travel it will.

I turn it over and use it for setting my my planner knives. My planner is a Delta 33 13 inch planner It has a cast iron bed. And just for reference the bed of the planner is the datum surface, again not the cutter head. I also use it to set the blade height on my table saw and for raising and adjusting cutter heights on my router tables. It lay on it side and I can set my miter gauge square. Lots of uses, I would be lost without it. I also make very fine moves on my rip fence.

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[Kevin Jenness]

https://oneway.ca/products-category/...us/Multi-Gauge

[Tom Bussey]

Brian,

It total indicator run out (TIR) from side and rotational also As you move it from side to side and also rotate the cutter. It doesn't need to be that close

I prefer knives to carbide inserts. They cut with less pressure so it is easier to get a board flat. I change out knives about once a year. It is next to impossible to machine all the pockets the same it for nothing but cutter wear and all the inserts are sintered and if you magnify your surface it will look like Bucky Beaver chewed it Anyway those are my two main reason not to change. Did I mention I sharpen my blades on a surface grinder so there is no cost to me.

[Bob Jones 5443]

I’m about to mill maybe 40 board feet of hard maple — half of it down to 5/8” thickness — and I haven’t changed my jointer or planer blades in a while. This process is intimidating for me. I know the work would go smoother with sharp knives, but I’m not confident I’ll achieve the setup I need for good work. I have no complaints about the surfaces I recently got with pine, but maple will ask more. I wish I could have someone who knows what they’re doing come by and tune up the two machines.

It’s not fun to admit this.

[Simon Dupay]

I have one thing to say taking off only a 1/64th at a time is hard on your knifes, the chips take away the heat from the cut, a 1/32ed is minimal for good knife life

[Robert Hayward]

https://oneway.ca/products-category/...us/Multi-Gauge

For a version a little more wallet friendly.

[Mark Hennebury]

A well explained method Tom.

I always set my knives using a stick of wood instead of a dial indicator.
use any stick , maple is always good, no particular size, 1-1/2" square 8-10" long.
Put two pencil marks on one side a couple of inches from the end. The photo shows three marks, the first one is not necessary.
raise the knives until they barely touch the wood.
When you rotate the cutterhead by hand it should move the wood from the first mark to the second.
Repeat, along the knife and for all knives.
Check as you tighten.

Then you can joint /hone to micro-tune to the exact height with a sharpening stone as in the second photo.
A couple of ways to do that.
Position the blade edge ahead of top dead center, clamp a stop on the infeed table, I use a thin flexible 12" ruler, so that It can stay in place for all of the knives. as it can just flex up to position the next knife.
Tap a wooden wedge in to keep the cutterhead from moving while you hone a micro bevel. This method gives you pretty good accuracy, a high quality edge and a clearance angle.

Another way is to not use the stop, and just hand rotate the cutterhead under the hone, this removes the clearance angle.
It will give good accuracy and a good finish as long as you only have a very tiny honed edge, just to get the knives in the same cutting circle.
If you have anything more than a really small micro bevel, you will find that cutting will be hard and vibrate the wood, as with no clearance angle the wood will be riding on the heal behind the cutting edge..

Third way, probably frowned on by many, is to do the honing with the machine running. A very high level of danger, do-able, but not recommended or everyone.

not my photos, they are from the websites listed below.

https://www.woodmagazine.com/tuning-up-your-jointer
https://www.finewoodworking.com/proj...nives-in-place

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[Kevin Jenness]

Mark, that's an excellent method for safely jointing the knives in place. It would be a good idea to tape the stone where it rides on the infeed table.