Jointer Lesson

[Bobby O'Neal]

So I'm a noob who's wanting to learn more about the milling process and eventually save up and buy some equipment. Reading up on jointers and planers, I'm coming across terms that are new to me. So...what are parallelogram beds on a jointer? Also, the term shelix/helical head? No clue on that one. What about the differences between spiral cutting blades and straight blades? Thanks all.

Bobby O'Neal

[Glen Butler]

Two quick google searches will yield a picture that will be worth a thousand words.

Helical Heads
http://images.google.com/images?hl=en&q=helical%20head&um=1&ie=UTF-8&source=og&sa=N&tab=wi

Helical heads are opposite straight knives (typically of high speed steel). Helical heads are preferred because of the cleaner sheering action cut and the carbide inserts remain sharper longer.

Parallelogram Jointers
http://images.google.com/images?um=1&hl=en&tbs=isch%3A1&sa=1&q=parallelogram+jointer&aq=f&aqi=&aql=&oq=&gs_rfai=&start=0

Parallelogram jointers are opposite dovetail way jointers. The table raises and lowers via two linkages that form a parallelogram with the base and tables. Dovetail jointers raise and lower the table via a sliding slope.

[Bobby O'Neal]

Thanks, Glen. So what is the advantage of the parallelogram?

[Chris Kennedy]

I should point out that I am not speaking from experience, just my own research.

Parallelogram jointers are supposed to be easier to adjust. If you are going to be changing the heights of your tables fairly regularly, a parallelogram jointer is the way to go. If you are likely to set your tables once and not change the heights very often, then you don't really need the parallelogram feature.

Cheers,

Chris

[Rod Sheridan]

I'm really at a loss to understand how a parallelogram jointer could be better than a dovetailed way jointer when it comes to changing table height.

On either machine a lever or handwheel raises/lowers the bed.

I owned a General 8" jointer for almost 2 decades. It's the "old" dovetailed way machine, and I never had any issues with table raising, or accuracy of the machine. I lower the table for deeper cuts, raise it for the final pass at a lighter cut. No problems.

It may be easier to adjust the tables initially to be coplanar on a parallelogram machine, however that's an initial setup issue.

Their are many dovetail way jointers in use 80 years after manufacture, so I wouldn't worry about purchasing one.

Regards, Rod.

[George Brown]

I have a parallelogram jointer. It is just faster and easier to adjust. Dovetail ones are no better or worse, just a little slower to raise and lower. Also, parallelogram ones don't need gibs to adjust play on the dovetails.

[george wilson]

I agree,Rod. Frankly,if the regular old jointers are ground after assembly,they are very accurately parallel and aligned with each other.

I THINK that early on Grizzly had problems with jointers that they had tried to grind before assembling the tables.

The millwork Shop in Williamsburg spent big bucks on an 8" Powermatic jointer about 2 years ago. The tables were GROSSLY out of parallel. I mean,nearly 1/2" sag on the outfeed table at the far end when I put my precision straight edge across the table.

I had advised them to buy a jointer like my Bridgewood for about $800.00. They spent over $2000.00 I think. It was still Asian,for Pete's sake !!! I bought the CHEAPEST 8" jointer that Grizzly makes for the toolmaker's shop before I left. It was dead accurate everywhere. Our old 1950's Delta 's tables were worn enough to be troublesome.

[JohnMorgan of Lititz]

I'm really at a loss to understand how a parallelogram jointer could be better than a dovetailed way jointer when it comes to changing table height.

On either machine a lever or handwheel raises/lowers the bed.

I owned a General 8" jointer for almost 2 decades. It's the "old" dovetailed way machine, and I never had any issues with table raising, or accuracy of the machine. I lower the table for deeper cuts, raise it for the final pass at a lighter cut. No problems.

It may be easier to adjust the tables initially to be coplanar on a parallelogram machine, however that's an initial setup issue.

Their are many dovetail way jointers in use 80 years after manufacture, so I wouldn't worry about purchasing one.

Regards, Rod.

I thought one of the advantages to parallelogram beds was when you do adjust up or down, the leading edge of the infeed table remains the same distance from the cutter. A tighter gap would probably help control tearout to some extent.

But, as you pointed out, there are older dovetailed-way machines out there with no issues. So what is the true advantage? I don't think there is one.

I happen to have a Grizzly parallelogram and bought it because it was supposed to be better. I rarely adjust the infeed depth, but when i do, its easy peasy and no handwheels to crank...just hold the lever and lift or drop to adjust - lock it down.

[glenn bradley]

P-beds was the #2 item on my gotta haves when I upgraded my jointer (spiral carbide insert cutterhead was #1). This is a bit of a Ford vs. Chevy argument unless you've ever had trouble with dovetail-way beds. Both designs are fundamentally sound. P-beds are easily adjustable without shims and a lot of swearing . . . oh wait, that's just me. Not everyone swears while doing these sort of adjustments ;-)

There is some touted benefit to the tables staying the same distance from the cutters despite the depth of cut (due to the way p-beds work). I am not sure how much value this has in practice as my jointer cut depth rarely exceeds 1/8" per run.

In case it helps; after saving my pennies for about 18 months (over which time I read every magazine and web review, owner's report and bashing article I could find), my list was like this:

1 - carbide insert spiral head
2 - long parallelogram beds
3 - tall fence that tilted in and out
4 - plenty of power
5 - magnetic switch
6 - mobile base

1 through 4 were deal-breakers (gotta-haves). 5 and beyond were adjustable. YMMV ;-)

[george wilson]

As a toolmaker,I think that the chances of making a parallelogram planer's tables out of parallel are greater than those of making the usual type jointer. Too many holes and other things must be made very accurately compared to the ordinary type.

[George Brown]

As a toolmaker,I think that the chances of making a parallelogram planer's tables out of parallel are greater than those of making the usual type jointer. Too many holes and other things must be made very accurately compared to the ordinary type.

There's adjustments for all that. Pain in the you-know-where, but there are adjustments. And you only have to do them once, at least I never had to readjust. Actually, mine came in correctly adjusted from the vendor, even after shipping they were not misaligned.

[Greg Portland]

There is some touted benefit to the tables staying the same distance from the cutters despite the depth of cut (due to the way p-beds work). I am not sure how much value this has in practice as my jointer cut depth rarely exceeds 1/8" per run.Agreed, with normal usage you typically only take off a little at a time. I found the p-beds to be a big plus when cutting rabbets on my jointer. However, the fence (on a DJ-20) did not slide forward enough so a sub-fence & outboard support had to be added. After some time I started using a router table or dado blade in my TS to make those cuts (safer & faster setup, the jointer was still a faster cut though). A shaper would of course be the optimal method for this operation.