Log-to-Dowel Jig

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Forum topic by RobinDobbie posted 06-07-2015 06:33 PM 1001 views 0 times favorited 6 replies Add to Favorites Watch
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147 posts in 1941 days

06-07-2015 06:33 PM

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Saw the Cylinder Mill, got excited about how freakin’ simple it looked, and immediately decided to build my own out of 2×4s and random hardware. Turns out, it’s not as simple as it looks. The Cylinder Mill is actually fairly well made, and what I have is a pile of failure. I’m determined to make this work, however!

To get this to work(at all, much less “well”) I need to make at least a couple of changes. I need a handle so I can turn it manually. I also need to remove the coarse threads on the opposite end so that the “tailstock” doesn’t force itself out of the end of the log, since I can’t find a hanger bolt with left-handed threads.

To make this work more accurately I need to change the method of holding the jig to the unistrut rails. The washers I bought are far too flimsy. They simply flex too much when I tighten the jig down, throwing the bushings out of alignment. Also, if I continue with a threaded power source, I need to find a more practical way to accurately drill into a log(while keeping the power hole in line with the “tailstock”). As it is, I remove the shafts from both ends and drill into the log through the bushings. This would work except that it’s a pain in the rear due to the drill chuck wreaking havoc on the threads of the relatively soft rods. Getting those nuts removed is a real chore. Also, because I have to use a 5/16” bit to make a hole for a 3/8” coarse thread(in a 3/8” bushing), perfect alignment isn’t possible.

Another accuracy problem is the fact that the power is coming from a threaded rod. Even if the threaded rod was perfect, adding the hangerbolt at the end with a coupling nut is just asking for problems. Also, oak does not a good bushing make, even if I had a perfectly sized drill bit for the threaded rod. I actually improved slightly on the first bushings I made. The first ones were simply a 3/8 hole drilled through the oak. Problem with that is 3/8 rod is not 3/8ths. I improved those bushing by drilling 5/16s, then used the 3/8 rod with jam nuts to slowly make the bushing bigger by stripping out the 5/16” hole 1/4” at a time. I’d screw the rod in about 1/4” at a time and once the nuts hit, I would keep going and blow out the threads. This made the hole only slightly larger than the 3/8 rod. Still, not the best way to make a hole.

So, I have some improvements in mind, but I’m open to any and all suggestions!

6 replies so far

View REO's profile


929 posts in 2280 days

#1 posted 06-07-2015 08:42 PM

kinda lucky it didn’t happen further into the cut or you would have been wearing the whole rig in your lap! Perfect alignment doesn’t come into play on this piece of equipment. the centers could be way off and it would still turn a cylinder around the center of rotation that would be formed y a line from one center to the other. A wobbly dado blade will cut much easier but it will also give you a rougher finish. use panels instead of open framework foryour jig. I would use at least 1/2” rod for the size you are working with. use a sleeve around the rod and a bushing around the sleeve. double nut the threads to prevent it from un threading.

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Bill White

5135 posts in 4166 days

#2 posted 06-07-2015 09:19 PM

Scared me and I’m fearless.


View RobinDobbie's profile


147 posts in 1941 days

#3 posted 06-07-2015 09:36 PM

I suppose I should have been more scared, but I know larger pieces are safer than smaller pieces simply because there’s only so much momentum in a saw blade. The mass of the log alone would keep it from getting flung too fast, but the jig weight is at least as much. So, that’s part of the reason I chose a larger test piece as the very first go.

“Perfect alignment doesn’t come into play on this piece of equipment.”

I understand your line of thought on that, but with my current power delivery method, I’d be making an oval. Any lathe with runout will result in a piece that’s out of round. I knew that, and I know there’s tons and tons of runout, but my first couple of uses for this jig won’t be affected by that. I do, however, want to eventually eliminate runout. In order to do that, I’m going to have to come up with a better way to get the log to spin. I know I can make a tailstock out of threaded rod with a fine point on the tip, jam it into the wood, and as long as the point doesn’t move during rotation, I will get a perfect circle(at least on that end of the jig). If the power end has wobble, then the log will slowly become more ovoid toward the front.

I definitely agree 1/2 rod would be better, but can I get a 1/2” bushing that will perfectly handle “1/2” threaded rod? My experience 3/8” makes me wonder how easy that will be.

“use panels instead of open framework foryour jig.”

That would certainly shore up the stability, but it would also limit the diameter of the log I could turn. I had a fantasy of turning 20”+ stumps into cylinders.

View REO's profile


929 posts in 2280 days

#4 posted 06-08-2015 01:54 AM

lathes with run-out do not create an oval turning. run-out makes it harder to turn concentric when a part is rechucked. run-out is not out of roundness. Run-out is the deviation of the axis of the tool, chuck, or cutter from the actual axis of the bearing. A boring head has a tremendously variable amount of run out but still makes a round hole. you will get odd shaped parts from a loose fastener or guide hole but that is not “run-out” that is just “slop”. lol. further into the cut the blade would have had more time to accelerate the mas of the log and frame. I worked for a sawmill where we installed a gang rip saw and had to design capture and energy dissipation for a 600 pound railroad tie going 100 miles an hour. surprising what some power and the grip of the saw teeth can produce! I have done a couple peices of equipment that take a log and make them round either in part or whole. one was used for putting the tennons on log furniture: we used a radial arm saw with a center at the saw end and a makeshift tails tock that provided the spin with a cog belt drive. turn it on and advance the saw on its own track to the desired depth. back off the saw and you have a tenon with a sweep the radius of the circumference of the blade. I believe you are looking to make the entire length round though. the diameters you are looking to do may require you to capture the track to prevent it from coming out of the miter slots especially if you want to run a lot of these. Specific spacers could be spendy but check with local hardware store for fits of bolts in pipe nipples, then drill ID to fit with your hand drill. with the original ID to help guide you you should be able to get close enough to make them work. Use fender washers on the pressure side of your oak bearing block to provide a large bearing surface. diameter wouldnt be restricted by the panels….make the box bigger!

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147 posts in 1941 days

#5 posted 06-08-2015 03:38 AM

The video:

Well you’re right. My calipers suggest these are .008” from perfectly round. That’s better than I get with store-bought dowels of a much smaller size. I don’t understand simple physics, it seems! So weird that I can see the shaft wiggling around unpredictably 1/16 – 1/8”, and it can still make a nice circle. Only problem is I ended up with a slight cone. One end is 1/4” wider. I think this is because I took the hangerbolt off the back, and also that bushing is slightly tighter than the front, so there’s less slop.

“further into the cut the blade would have had more time to accelerate the mas of the log and frame.”

If I had a more powerful table saw I might could see that. However, this is a 1.5 HP saw with a thin kerf blade. Once the momentum of the 1 lb blade is spent, and the RPM is near nothing(like it was last night), I don’t see the continued danger. The motor strength at such a low RPM is almost nothing. If the saw was powerful enough to keep the blade spinning at 3450 RPM no-matter-what, then yes, I could see the potential danger of an entire log flying at me. Now there is a danger that even the properly made mill has, and that is smaller pieces flying off the main log. So I may put a little circle behind the handle so that my knuckles aren’t constantly getting pelted with little bits.

Never thought of doing something like this on a RAS, but I don’t see why not. Love to see that in action. And I think I’ll want to make tenons, too. Hell, maybe even profiles. If I turn the jig at an angle and raise the blade, I could get some interesting shapes.

“the diameters you are looking to do may require you to capture the track to prevent it from coming out of the miter slots especially if you want to run a lot of these.”

This doesn’t ride in the miter slots, but are you worried about it raising up in an accident, to just that longer logs might tip over the jig when being milled at their ends?

“….make the box bigger!”

I guess if I get really into it I could do that. I like the open nature of it even more after using it for the first time tonight. The amount of sawdust this thing creates is PHENOMENAL. I wouldn’t want to restrict it’s departure from the table saw if I could help it. As it stands, I had to stop half way and clear it out of the blade throat plate. I should have just removed the plate after what happened last night with a piece getting stuck in there as the blade slowed.

View TheFridge's profile


10767 posts in 1692 days

#6 posted 06-08-2015 03:59 AM

Yeah buddy!

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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