This morning was fix my router day

smorgasbord

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Long story long here.

Last week I set about installing MuscleChucks on my routers. This is actually a process you need to undertake to have reduced run-out.



In that video, the inventor claims that with two solid cones mating, you need to find the right positioning such that they're mating properly. A normal collet is flexible, so it almost always mates easily. The MuscleChuck itself is a hard cone, so you've got cone within cone.

I dug out my dial indicator (not an expensive one that he has, but mine has 0.01mm gradations (0.0004" , aka 4 ten-thousandths) and did as he did, measuring against the inside cone of the router spindles while rotating them by hand. Good news was that the Makita trim router in my CNC was good to within +/-0.005mm (dial went from 0 to 0.01mm), and the venerable Porter Cable 7518 in my router table was almost as good (about +/-0.0075mm).

I then did the install the chuck, install a straight bit, and put the dial indicator on the shank near the collet and rotate by hand. Now the bit sticking out will magnify any run-out, but after a few tries I got that minimized to about +/- 0.025mm on each.

I then went to my hand-held router, which is a decades old Bosch 1613EVS. I bought it because I liked the micro-adjust mechanism, which is operated with the plunge locked, and graduated in 0.1mm (1/256"). After a few years of use, I dropped it onto a concrete floor. It landed on the attached edge guide, which snapped a piece of the base that held the nut that secured one guide rod, and also bent the base a tad. I was young and stupid, and didn't think then to just order a new base from Bosch, so I bought another 1613EVS and put the old one on a shelf, thinking I'd jig it up for some dedicated use later (never did, unsurprisingly).

Well, I was never totally happy with the quality of cuts I got with my newer 1613EVS. Doing the run-out check exposed the problem: the shaft had radial play, about 0.08mm worth near the chuck. That may not look like a lot on paper, but it's enough to feel if you push on the side of a router bit in the chuck, particularly a couple of inches below the chuck. So, this morning I set about seeing if I could put the newer base on the older router since the older router didn't have that run-out/play.

Anyway, after taking them apart, I first thought it was the big bearing on the spindle near the chuck, but upon close examination, it turned out that the bearing had some play inside the router housing. The bottom housing was cast with 8 small protrusions in the hole, which were then milled down to accommodate the bearing. That milling process must have been sloppy in the newer router. I was going to just put the older housing on the newer router, but Bosch changed the depth stop and markings between my two versions and I liked the newer version better. I ended up sticking a piece of thin feeler gauge between the milled protrusions and against the bearing's outer wall to remove the play.

As I expected, getting the router back together was a bit of struggle. Besides compressing springs, I had to remove the brushes to get the spindle back into the top housing, and had to press the plunge lever (duh!) to push the halves together. But, now the router doesn't have play in the spindle and I've got the chuck run-out down to acceptable levels. I even got the other one back together, and it still runs, too. I'll hide it on a back shelf in case I need other parts to cannibalize from it later.

Looking at how the Bosch is constructed, I guess I feel better about radial run-out, but wonder just how vertical the vertical plunge mechanism is, or perhaps I should say how perpendicular to the base the plunge action/axis is. I could probably rig up the dial indicator to measure, but having spent hours doing nothing but futz with my routers, I want to get back to actually cutting wood.

Notes on the MuscleChuck:
• Very convenient way to change out bits, just a 4mm hex wrench (3mm on the Makita trim) and maybe just one full turn. No spindle lock needed.
• On the CNC, it's a godsend because you're not fighting collet nut torque and have a spare hand to catch the bit.
• Actually, often don't need to catch the bit because the shank's fit in the MuscleChuck is almost air tight and so vacuum holds it in place.
• On the router table, I no longer need two wrenches, one of which was offset.
• I had originally bought the extended chuck for the router table, but that wasn't needed and only reduced my effective travel. I'll put it up for sale (Type 1E).
• On the bad side, even the regular Muscle Chuck extends further than the standard collet, so you do lose some effective travel. On the CNC, that's not a problem since I can just mount the router a tad higher, and the router table we'll see if that becomes an issue, and hand-held it'll allow me to make a thicker sub-base since the chuck can be lower than the standard sub-base now.
• I should have, but didn't take measurements on the bit shanks with the standard collets, so I can't compare run-out specs. I feel the standard collets might be better, but we're talking one or two ten-thousandths of an inch here (hundreths of a millimeter).
• The MuscleChuck is a ½" chuck (¼" on the Makita trim). To use bits with other shank diameters, you need an adapter sleeve. MuscleChuck sells some high quality sleeves, so I got a set (⅛", ¼", ⅜", 8mm). This is good in that you don't need to buy additional chucks, but does slightly complicate bit mounting.

As for routing, I'll have to see how satisfied I remain with the 1613EVS. I should probably eventually get an OF2200. And then either an OF1400 or the DeWalt 620B battery router for the mid tasks if the 1613EVS disappoints.
 
I like the idea of this for the CNC but just never got around to it.

Have to pull my finger out and get cracking, as you note, changing cutters on the ER collets is a 3 handed job.
 
I think MuscleChuck is limited to ER20 collet replacements. Two different thread pitches, though.
 
I like the idea of this for the CNC but just never got around to it.
So, having used it for the past couple of weeks, I've decided it's not a good match for my CNC.

I'm running a Shapeoko, which I like, but it uses a Makita trim router, for which MuscleChuck makes a specific ¼" chuck. While the hex bolt is very convenient for mounting/dismounting router bits, it extends the collet quite a bit below the router's threaded shaft. That messes up my Z-axis zero point, which I could fix, but it also messes up the dust boot, which now often doesn't have enough router body to clamp onto. And by extending the shaft, I think it makes any slight run-out or imbalance that much worse. Finally, it doesn't support 8mm bits - and I do have an 8mm collet for the Makita.

So, I love the MuscleChuck on my table mounted router and think I'll like it on my mid-sized hand-held router, but for the trim router in a CNC, it's not for me.
 
@smorgasbord That's a shame, it's always trickier with the CNC. I bought a 60 degree cutter not long back with a replaceable insert, but the vibration was just terrible.

It was just unusable, and it's not of much value to me for use in a hand held router sadly.
 
Are both of you using two hands for two wrenches? That would explain the lack of hands.

I always use one hand for two wrenches, first aligning the wrenches so they are slightly non-parallel. Then I can just squeeze them together with one hand to loosen the nut. (Or tighten the nut, depending on the direction of the initial non-parallelity.)

Apart from the advantage of having the other hand free, this feels much more controllable and smooth. There is no sudden jerk when I overcome the resistance and the nut starts to loosen. I actually prefer this method over using the spindle stop with one wrench.

But I will agree that the hex key solution sounds even more superior.
 
And by extending the shaft, I think it makes any slight run-out or imbalance that much worse.
I must admit that I was a little baffled when I read your first post. You were so dedicated to minimizing run-out, and then you installed a collet extension.
(I understand that this one is not really meant to extend, but it is still one more connection).

Also, though perhaps this is a bit of a puristic view: When looking on Musclechuck's website, that tightening mechanism seems a bit asymmetric to me. If the shank is not exactly on the correct diameter for the chuck, it will be slightly offset from center when tightening the chuck.
 
Interesting points.

I did the runout testing because I was mounting MuscleChucks. Their interface has to mimic the collet, but that creates two hard, unyielding mating surfaces, so it often takes a rotation after first installation to get them to seat perfectly. While I think it would be great if some company adopted the MuscleChuck design and built that into a router shank, this is what we've got. The extra extension is actually great on the router table, and on some hand-held routers where the collet doesn't reach the bottom of the sub-base by default. I've only found it a problem on the small trim router.

As for the asymmetric design, I think router bit shanks, at least for good quality bits, are ground to a pretty high precision. Amana says:
For example, the shank of an inexpensive bit is often undersized from sloppy machining; this can cause the bit to slip in the collet and spoil the workpiece. In contrast, Amana router bits are precisely ground no less than 0.002” under the collet dimension (PHOTO 1). This ensures that the collet can firmly grip the shank of the bit.
One of the MuscleChuck videos shows that with a bit inserted but not tightened, the tolerances are tight enough that the bit won't slide out due to air suction/vacuum. I've seen this myself, and you can feel the suction as you pull a bit out to change to another. I haven't seen the technical drawings of the chuck, but I don't think the clamping portion even on a slightly undersized bit would be non-concentric enough to measure with our regular shop dial gauges. At some point you have to weigh the tolerances of the shank and collet versus the MuscleChuck.

Another reason for the MuscleChuck is to get the right clamping forces. They have specific installation instructions (you can even use a torque wrench), and afterwards, the hex bolt tightening is straightforward and doesn't require much torquing at all. So if hand strength is an issue, it might be a really great choice. Of course, Festool's ratchet mechanism also seems very good.
 
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