Router base close call

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Forum topic by NBeener posted 03-11-2010 12:42 AM 3417 views 0 times favorited 20 replies Add to Favorites Watch
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4816 posts in 3141 days

03-11-2010 12:42 AM

I had the dovetail jig out, today, to make my nephew a carpenter’s tool box.

I had made a base for my Ryobi RE180PL plunge router (out of ply). I’ve used it before, successfully.

But … today … I had to swap out the dovetail bit and 3/4” bearing—the only setup I’ve used, so far—for the 5/8” bearing and straight bit (to cut the pins in full dovetails).

When I started the router to make the first pin, all hell broke loose.

With a little time, here’s what I figured out:

The hole that I cut in the center of my shop-made base was ever so slightly off-center … probably by about 1/32”.

This was just fine for the larger bearing, but … once I shrunk down to the 5/8” bearing, the shank of the straight bit must have just touched the bearing’s slightly narrower inside diameter.

What this did was … to unscrew the collet AND the lock nut (for the bearing). Both the bearing AND the bit came out … with a fair bit of unsettling commotion.

I had the plexiglass ‘guard’ on my router, and my safety glasses and leather shop apron on, so … the ‘damage’ was totally contained.

But … I realized this—like so many others—could have been much worse.

The project’s on hold … until my “store-bought” 3/8” acrylic base arrives.

Just another thing to be conscientious about … when working with routers, bearings, bases, and templates!!

-- -- Neil

20 replies so far

View mtkate's profile


2049 posts in 3293 days

#1 posted 03-11-2010 12:59 AM

Oof. Even when I turn on my router in the table I stand way back and make sure there is something between me and it to hit… And I am not brave enough to free wheel it like you are trying to do…

View Jim Bertelson's profile

Jim Bertelson

4170 posts in 3132 days

#2 posted 03-11-2010 01:03 AM

Deleted…......wrong mental image…...(-:

-- Jim, Anchorage Alaska

View Dick, & Barb Cain's profile

Dick, & Barb Cain

8693 posts in 4267 days

#3 posted 03-11-2010 01:04 AM

I’m glad you didn’t get hurt.

You could have had some dangerous shrapnel flying around.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN.

View Jim Bertelson's profile

Jim Bertelson

4170 posts in 3132 days

#4 posted 03-11-2010 01:15 AM

I was thinking you were talking about it in a table, now I am beginning to get the picture.

-- Jim, Anchorage Alaska

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Jim Bertelson

4170 posts in 3132 days

#5 posted 03-11-2010 01:41 AM

I don’t think I have used that feature of my router yet, but before I do, I am going to have to talk to you. Like Dick said, that was like shrapnel I am sure. Gad Zooks man….......get a Kevlar apron…............(-:

Your eyes are well….your eyes. But that apron was protecting some pretty important parts…............

-- Jim, Anchorage Alaska

View NBeener's profile


4816 posts in 3141 days

#6 posted 03-11-2010 02:01 AM

Just a little more info …

Here’s the basic process, performed with a free-hand router and the P-C jig:

Here’s a router bushing …

I had a 7” x 7” piece of ply with a hole cut … well … I thought dead center. That was my DIY router base.

One side of the bushing goes on the bottom, and protrudes through the hole. The lock ring secures the bushing in place from the top—the router side.

The router BIT, then, goes through the bushing, into the router collet, protruding from the bottom of the whole shebang.

The bushing “guides” the router bit through a template—in this case, the dovetail jig.

Extra info for those who are sure they don’t want to repeat my mistake….

Yeah. I’m moving to my motorcycle helmet and kevlar riding suit, next :-)

This stuff never happens to Norm …. ;-)

-- -- Neil

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4816 posts in 3141 days

#7 posted 03-11-2010 02:10 AM

Even more specific, and directly applicable info, from the NewWoodworker site.

[NOW he tells me ;-)]:

Clearance between router bit and guide bushing can be very small, making alignment of the two critical. In some applications, especially when used with a dovetail template, having the bushing centered in the router base, and returning to that alignment whenever the baseplate is re-installed, is very important. Fortunately, most baseplates fit the routers accurately, but if your baseplate is slightly out-of-line, checking and correcting it is usually simple.

Make certain the bit is centered in the bushing. Fixing a misalignment is usually easy.

With the router unplugged, install a bushing and a router bit slightly smaller than the bushings inside diameter (ID). Check to be sure the gap between the bit and bushing is even all around. I use the depth feature on my digital calipers for this measurement but you can get it extremely close by eye.

[NB: He doesn’t have MY eyes LOL!]

If the bit is off-center more than a couple of thousandths, try removing the baseplate mounting screws and turning it clockwise until the screw holes in the baseplate line up with the holes in the router base again. Re-install the mounting screws and check for even clearance around the bit again. In most cases, one of the possible mounting positions will center the bit within the bushing.

Once the correct position is found, scratch a line in the edge of the baseplate, and router base at one of the mounting screw bosses. Then, when re-installing this baseplate you need only align these marks and the bushing will once again be centered on the bit.

-- -- Neil

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4816 posts in 3141 days

#8 posted 03-11-2010 02:18 AM

Annnnnd, NewWoodworker goes on to specifically caution against what I was doing—exactly what Porter-Cable said I should do, and with exactly the materials included with my jig.

Go figure !

A word of caution: I always use a ¾” OD collar with a ½” bit because of the clearance this combination affords between the cutter and collar. Depending on the wall thickness, a 5/8” OD collar may only provide 1/32” clearance between the bit and the inner wall of the collar. Such tight clearance could cause problems if chips build up in this tiny space. With shaft speeds of 10,000 RPM or more, I want the extra clearance.

I hear ya, Tom. I hear ya’!!

I may have to re-think the hardware, in addition to the new router base plate….

-- -- Neil

View stefang's profile


15881 posts in 3302 days

#9 posted 03-11-2010 11:45 AM

Hey Neil. I’m glad you weren’t hurt as a result of this mishap. Steel guide bushings are notoriuous for not staying locked properly. That is why there are so many brass bushings on the market. They stay locked. I suppose this is due to the relative softness of brass.

-- Mike, an American living in Norway.

View Dick, & Barb Cain's profile

Dick, & Barb Cain

8693 posts in 4267 days

#10 posted 03-11-2010 01:09 PM


I didn’t realize you were talking about guide bushings.

Some bits can’t be used with guide bushings because of their size.

I have this set of guide bushings from Harbor Freight.

They are a very good buy for $19.99.

They are very accurately made, & I recommend them.
Router bushing set

Some of the bushings are kind of long, so I had to cut them shorter for some applications.

It also comes with an adapter plate, so if you make your own router base, or table, it’s 100% accurate.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN.

View lumberdustjohn's profile


1263 posts in 3134 days

#11 posted 03-11-2010 02:20 PM

Glad your O.K.
Did you damage the wood?

-- Safety first because someone needs you.

View NBeener's profile


4816 posts in 3141 days

#12 posted 03-11-2010 05:28 PM

Yeah. I’m nearly dangerous when I try to use woodworking terminology.

Even though I knew what I meant (LOL!), I figured a few pics might help :-)

Mike: Yet another A+ for you, Kind Sir. That’s exactly what I read: brass stays secure, better. If using steel, use pliers.

The OEM Porter-Cable are steel. The Milwaukee set I bought are also steel.

Dick: Thank you very much for that. Not that I really NEED another reason to make a HF trip, but … nice to have one! I’ll snatch up a set of those, pronto.

The adapter plate makes it all worthwhile, for the exact reason you stated.

Since the original guide bushing + straight bit combination that caused the little episode were both original equipment with the Porter-Cable 4212 Dovetailing Jig, I’m hoping they weren’t a bad combination.

Knowing me …. eccentricity (in ever sense of the word) in my shop-made router base seems far more likely.

John: Trashed it LOL!!

But …. after heading back to the shop, last evening, to take another whack at it … the other thing I found is … it seems fairly commonly agreed to (or just believed) that using a dovetail jig to cut dovetails in baltic birch plywood is a BAD idea.

Tear-out, tear-out, tear-out!

Even on the router-specific forums, their “resident experts” talked about which brand of bit, pre-scoring the bottom line, climb-cutting THEN reversing direction, using backer boards on both sides of BOTH boards, etc., etc.

Their bottom line seemed to be … don’t do it. I went through about 10bf of the BB ply before I turned to the Internet.

My nephew’s carpenter’s tool box deserves hardwood, anyway …. ;-)

Thanks, All. Great feedback!

-- -- Neil

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Jim Bertelson

4170 posts in 3132 days

#13 posted 03-11-2010 06:03 PM

Thanks for the heads up on the bushings and the BB. This is something that I could easily get trapped in as well since I make a lot of things rather than buying them…...mostly to prove the point that it can be done….....(-:

Out working last night again, although I wasn’t on call and usually take Wednesdays off. No shop time since Sunday. It has been a demanding week. I should be done around 1400 hrs today, here’s hoping.

-- Jim, Anchorage Alaska

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117063 posts in 3544 days

#14 posted 03-11-2010 06:09 PM

Glad your ok Neil

-- wood crafting & woodworking classes

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409 posts in 3439 days

#15 posted 03-11-2010 07:22 PM

Neil -

Use a centering cone to align the plate and collar.

Also consider adding a wave washer between the collar nut and the collar to keep the nut from vibrating loose.

And as always, remember to RTFM no matter how poorly written the manual… ;)

-- Don't sweat the petty things and don't pet the sweaty things.

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