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Delta 36-979 Blade Retraction Solution

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Forum topic by PPerry posted 09-10-2019 03:33 AM 421 views 0 times favorited 11 replies Add to Favorites Watch
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PPerry

17 posts in 365 days


09-10-2019 03:33 AM

Topic tags/keywords: 36-979

I acquired a lightly used Delta 36-979 (similar to the 36-981 pictured) Tablesaw and the 10” blade would not drop completely below the table top.

I didn’t measure how high it protruded but I’d guess the blade was maybe a 3/16” high! It was a lot. Thinking there was an adjustment, and not having the manual, I just Googled it, and another person posted the same problem a few years ago. It may have even been this forum, I forget. There was no solution offered in that short thread.

Upon inspection, I found the retractable casting that holds the blade shaft to be hitting one of the two support bars below it when completely lowered. (see red arrow in picture)

The mechanism has two cap head allen bolts that are supposed to act as stops but even after removing the one marked by my yellow arrow the blade tip would not go below the table.

I took the guard off an angle grinder and carefully gouged a moon shaped relief in the casting so it would drop lower. (see green moon shaped area in my picture)

At this point the blade now drops about 1/32” below table top. I might be able to take just a tick more off the casting, but instead I’m going to extend the existing relief flat on the shaft that it was hitting.

The existing flat is to prevent the blade shaft from hitting the support shaft, and if they had machined it just a little more along the length, it would have helped the whole situation as well. (see tiny blue line next to green area I where I will increase the flat)

I thought maybe the second shaft to the left (not pictured) might be different, and perhaps they were swapped accidentally during assembly, but they both are the same exact part. Either that or a wrong part was substituted at the factory.

I’ll probably use a file or something more controllable to extend the flat rather than the angle grinder.

It would be nice not to have to use the dado blade to hog out and/or make my piercing through my new zero clearance inserts, but after I file the lower shaft I think I will still be a bit high to avoid that task.


11 replies so far

View Sylvain's profile

Sylvain

880 posts in 3005 days


#1 posted 09-10-2019 07:31 AM

Matthias Wandel has interesting blogs about tuning table saws.
In this one he tunes a Delta one, although another model.
Seeing how the trunnions are fixed to the table, you might have been able to lower the complete mechanism by inserting washers between the trunnions and the table.

-- Sylvain, Brussels, Belgium, Europe - The more I learn, the more there is to learn

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PPerry

17 posts in 365 days


#2 posted 09-10-2019 12:39 PM

Thank you for the link. That route may give me even more ability to lower the blade should I decide to pursue it in the future. I’ll look this evening and see if my setup has any washers in place already or not.

View PPerry's profile

PPerry

17 posts in 365 days


#3 posted 09-10-2019 12:49 PM

Also I wanted to note that it appears I ground a lot off because you don’t see the remaining back side of the casting. If you look carefully, you can see I only ground up to the edge of an already existing chamfer which due to its angle really did nothing to help clearance.

View CaptainKlutz's profile

CaptainKlutz

1883 posts in 2000 days


#4 posted 09-11-2019 05:41 AM

FWIW – On Delta Unisaw, the lowered blade height is adjusted by changing the fwd to back location of the pinion gear that drives the pawl gear on arbor. You simply loosen the nut on end of shaft, which makes the rod longer. Then you loosen set screw on retaining ring to remove the play in shaft. This moves the pinion closer to front, which lowers the blade position.

Can’t find your saw’s owners manual: But the couple of similar style Delta contractor saws it shows an adjustment on the shaft to remove play in height setting. Suggest you loosen the adjustment and see if you can change the lowered height.

Best Luck.

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

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PPerry

17 posts in 365 days


#5 posted 09-13-2019 12:47 AM

My mechanism is as Sylvain described above, with the trunnions mounted to the table. I do appreciate your advice about the UniSaw adjustment as my dad has a 1980’s or early 90’s Unisaw.

I took a few more pictures tonight and also took a grinder to the trunnion shaft to increase clearance. I’m glad I didn’t try the hand file, the steel appeared hardened. I now can get the blade about 3/16” below tabletop. Adding washers would have been a good option except I didn’t want to have to resquare everything.

These two pictures are rotated wrong but you get the idea of what I’m doing. I mounted the grinder wheel upside down to attack the shaft due to space limitations.

This blue circle shows how much I removed behind the existing flat. Even with all this removed I’m still safe and the spinning blade shaft cannot contact the trunnion shaft.

Also while inspecting underneath, I discovered something most may already know. There is slack in the gear on the handle shaft that adjusts the blade height until you tighten the locking nut. I assumed that the locking nut was just to keep the handle from moving should you bump it, but it also removes the play. (See two yellow arrows in picture below) I’m not sure it would make a lot of difference, but I will start moving the blade in a specific direction when I set my height. I’m not sure if I should go up and pass my mark, them crank the handle down, or just the opposite, to reduce the possibility of the blade creeping up or down and screwing with my accuracy.

View therealSteveN's profile

therealSteveN

3858 posts in 1080 days


#6 posted 09-13-2019 06:17 AM

DeWalt Service net page with the Delta 36-979 manual, and other pages.#

In the upper blocked in box on the right side, look for “Instruction Manual” choose the PDF looking object, and it will download the manual to your Downloads section.

This is something many TSs have in common, with a new uncut insert the blade isn’t low enough to allow the new insert room. There are 2 ascribed methods to deal with this. the first is simplistic, and has you use a 7 1/4” circular saw blade. Here the problem is blade Kerf width. If you have a full sized 1/8” kerf on your 10” blade, a circ saw blade will make a poor clearance for you. Repeatedly raising a 10” blade through that will often get you a ragged maw, not much different in width than what you are trying to get away from.

I use the second method and this is to use a router, and clear out a 1/2” of material from the BOTTOM side of the new insert, at the spot where the blade will come through. If you look at any aftermarket inserts, this is what they do. The insert will then fit over the blade, and you can proceed to make your cut.

Neither of those have you grinding the casting arms of you table saw down, to what Delta would probably argue is an unsafe level.

I will state I have a 36-979, which you have pictured, note the pic in the manual. The 978 is the stamped wings model. 979 has solid cast tables. Anyhow to the point. My blade sits just under the tables surface. If yours is above you may have allowed it to drop lower, by misguiding your depth sets, but you haven’t addressed the problem that has your blade protruding. Mine does not, as it shouldn’t.

I’d check this real quick, see where it has you, because there isn’t a whole lot else to adjust under there. With exception of the depth stop nut, which can be dialed in, and out. Once your blade shows a true 90 to the table, you keep it there, and adjust your blade tilt indicator to 90. This is the biggest issue with a contractor saw. While running, it tends to loosen both of these areas.

From page #16 showing the tension of the drive belt from the back end of the saw.

IMMEDIATELY AFTER ASSEMBLING
THE BELT, RAISE THE SAW BLADE
TO ITS MAXIMUM HEIGHT AND TILT THE SAW BLADE
TO 45 DEGREES. USING A STRAIGHT EDGE (M) FIG.
39, CHECK TO SEE IF THE MOTOR END (N) FIG. 39,
IS BELOW THE TOP OF THE TABLE SURFACE (O). IF
THE MOTOR END IS ABOVE THE TOP OF THE TABLE
SURFACE, LOOSEN THE FOUR HEX NUTS (F) FIG. 31,
RE-POSITION MOTOR AND THEN RETIGHTEN THE
NUTS. THEN, RE-ALIGN THE MOTOR PULLEY (K) FIG. 38
TO THE ARBOR PULLEY

Wishing you the best.

-- Think safe, be safe

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PPerry

17 posts in 365 days


#7 posted 09-13-2019 07:02 PM

Yes, my “979” is like yours with the cast top. Thank you for the link. There isn’t anything in there about my issue, but that’s good to have an extra copy. I think I got one in my stack, but it’s probably a bit tattered.

I studied prior about cutting the inserts and wholly agree about the methods to create clearance before final cut through. My issue was the blade wouldn’t even go level with the table, let alone below it. But anyway I don’t think I hurt it, that steel was super hardened and I cut no more off than what was already there for a wrench to fit (presumably) and or clearance for the blade shaft.

I would be curious if you could take a picture directly from below for comparison. I used one of those portable LED work lights to light it up. If you can, if not no problem.

View PPerry's profile

PPerry

17 posts in 365 days


#8 posted 09-13-2019 07:05 PM

I will check that #16 tonight.

Also curious how high your 10” blade will raise above the table in inches or millimeters. That should give me an idea if mine had limited travel prior or if it was an unknown adjustment.

View therealSteveN's profile

therealSteveN

3858 posts in 1080 days


#9 posted 09-13-2019 08:31 PM

It may be a while, it’s in the garage under a pile of stuff. I’ve never cut anything with it full height. Having BS’s I resaw with them. The books used to say 3.5” at 90, but they have long been replaced with the current gibberish if you note doesn’t have this info on it. Why??? I have no answer.

Just because of the strange relationship with tilt, and table movement with a Contractor, check that full height 45, and see if your motor isn’t high. I’m not sure I can explain it to you, but I think that is your Huckleberry. I believe if you lower the motor, the blade will also be lower, ending your tall blade issue. Because really there is nothing else, except the blade height limiter, and you seem to be aware of that, and I assume you’ve moved it to see if it allowed your blade to drop. In the manual, they only YELL at you on that motor height issue.

If that checks out ok, let me know, and I’ll dig in, and go to exact measuring on mine. I’ll check back.

-- Think safe, be safe

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PPerry

17 posts in 365 days


#10 posted 09-13-2019 09:40 PM

Thanks again. Yeah, I never ever plan to cut full height with it. I have a bandsaw as well, though don’t see myself doing a lot of resawing any time soon. I was just thinking the full height measurement might tell me if I have as much total travel as yours. In other words, if before I messed with it, would my blade go ~1/4” higher above table because it was already ~1/4” proud of the top at lowest setting.

Yeah, I completely removed that allen head limiter which had no effect. I will try putting it back in now that I’ve increased drop clearance and see if it stops on it or not. At any rate the trunnion is still acting like a “stop” and there is no way for the spinning blade shaft to contact it.

I will check/adjust the motor. The belt that came with it has a “set” in it from sitting for 5+ years and I’ve been thinking of replacing it with a linkbelt from HF. Not that I need that improvement but I’m more curious than anything about how it will react.

View therealSteveN's profile

therealSteveN

3858 posts in 1080 days


#11 posted 09-14-2019 02:43 AM

My opinion is leave the HF link belts at HF. I won one of their BS’s and used the supplied link belt, and the machine on start up literally walked across the concrete floor. I switched it to a red Fenner drives belt, and it instantly could pass a nickle test. Truth be told if you could get a dime on edge, running the saw wouldn’t knock it over, including start up, very smooth. With that HF belt you could shake paint.

-- Think safe, be safe

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