Car Analogy for Jointer Decision... Help...

[JayStPeter]

Rick,

I partially agree with you. As an engineer, I tend to analyze designs and have done so in my jointer research. The parallelogram design is clearly superior. I think it is especially so over the looong term (and larger machines). I suspect if you take a Grizzly 1018 and a DJ-20 and subject them to a decent amount of use for 100 years, the DJ-20 will come out much better.

I personally don't know the actual effect of having the tables closer to the cutterhead. First, are they significantly closer in the small range that we actually use them? Second, does it actually make a difference in tearout? Probably, but to what extent I don't know. My feeling is that the new helix cutterheads make a bigger difference. So, that is the route I've chosen.

Dovetail ways do wear. The 1960s Rockwell 6" I restored is proof positive of this fact. They have adjustments built in to take up this wear. Not a great design, but it works. If I was running the thing day in and day out, I would want a parallelogram design to minimize the hassle/lost productivity associated with adjusting the ways (and more importantly ruining parts before realizing it). But, in my hobby shop, it is years between adjustments. Heck, I don't even know how many years yet. I do know that the locknut adjustments on my Grizzly is a much better design than the little mini-screw adjustment on the old Rockwell. Without locktite, that thing could vibrate itself out of adjustment in a couple hours.

For a jointer larger than 8", I would definitely start looking at parallelogram design. I think the added mass would cause more wear and the larger heavier tables are more likely to sag. As you mentioned, the ability to remove the tables and have them surfaced individually is a big plus. I don't think there are too many large jointers that don't use parallelogram designs. Most of the large old iron did too I think. You're right that Delta is not a "pioneer" of the design. But, they were the only ones to offer it in a smaller competitively priced model.

There are plenty of 50+ year old dovetail way 8" jointers still in use today. So, I think one with moderate use should last a good long time. There are some who say the modern Asian cast iron isn't as good as the old american stuff. They think these jointers won't last as long as the older ones. Maybe ... maybe not. It kind of makes me laugh. In 20 years, I wonder if people will be paying a premium on ebay for those great Taiwaneese made jointers from the 1990s saying "That cast iron is better than the new stuff" .

Jay

[Rick Lizek]

The older large machines of American origin do not use the parallelogram system found in the DJ-20 and such. They used dovetail ways or four small inclines under each corner of the table. Commonly found on Oliver, Crescent, etc. In a sense I would compare the small inclines to a parallelogram system as
The better ones with the dovetailed ways had four point individual adjusters for each table. The problem I found with the machines like the older Delta's with the dovetailed ways is the base is so small in relation to the length of the tables they tend to sag over time. Easily corrected by shimming the outfeed table but if there is a twist you can only split the difference unless you have the table reground if it's really off.

I'm not saying the Dovetailed ways are necessarily bad but the older larger jointers had longer more massive dovetailed ways to support the bigger tables. In comparison the six and eight inch models have very small bases in relation to the tables.

I don't find any advantage in chip breaking with the closeness of the tables. I think it's more of a safety thing. I had a 20" paraleleogram type jointer that I was repairing the replacable lips on and had the infeed one off and ran some curly maple with the extra wide throat and the was no noticable difference after I put the repaired lip back on.
The issue of the old square head was there was more chance of getting something caught as the opening was bigger every 1/4 rotation of the head. I remember seeing the warning pictures of fingers that were stuck under the edge of the the ends of the jointer table. I couldn't imagine anyone would do such a thing but after being in the business 35 years I believe anything could happen. The gibs have that hollow which has been designed to be the chipbreaker.

I've been using the insert heads on moulders and such and they do work nice but I've had just as good luck with curly woods by making sure the knives are sharp and using the right feed. I suspect many are bying the insert heads to avoid the dreaded knife change.

People will be buying the old Asian iron in the future.

[JayStPeter]

The older large machines of American origin do not use the parallelogram system found in the DJ-20 and such. They used dovetail ways or four small inclines under each corner of the table. Commonly found on Oliver, Crescent, etc. In a sense I would compare the small inclines to a parallelogram system as
The better ones with the dovetailed ways had four point individual adjusters for each table. The problem I found with the machines like the older Delta's with the dovetailed ways is the base is so small in relation to the length of the tables they tend to sag over time. Easily corrected by shimming the outfeed table but if there is a twist you can only split the difference unless you have the table reground if it's really off.

Ahaaa, I knew a lot of old iron had tables that could be shimmed on all four corners. Never saw the mechanism, just assumed it was parallelogram.

I've been using the insert heads on moulders and such and they do work nice but I've had just as good luck with curly woods by making sure the knives are sharp and using the right feed. I suspect many are bying the insert heads to avoid the dreaded knife change.

Busted, that's my real main reason for buying one

People will be buying the old Asian iron in the future.

Jay