Work(shop) in Progress #3: Bosch 4100 TS - Zero-Clearance Inserts

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Blog entry by PurpLev posted 07-06-2008 05:49 PM 21732 reads 14 times favorited 17 comments Add to Favorites Watch
« Part 2: Workbench: The TOP Part 3 of Work(shop) in Progress series Part 4: Finally the Band has arrived... (saw that is) »

I got a few questions about the zero-clearance inserts I made for my bosch table saw, so I figured I’d post the procedure here as to how I made those.

The basic Idea is to take the factory inserts and use that as a template for the router. but alas, the factory insert is just too thin at some points to be able to follow it with a trim router bit, so to tackle this issue I made an initial template out of 1/2” plywood. This first template took a bit more patience and care so that it matches the original shape perfectly. Once I got this 1/2” ply template I am set for as long as I need to make inserts as I can always use that template easily with a trim-bit.

Notice how the bottom face of the template has a groove in to allow the blade to fit in – this is merely done so that I could push the template in and check for precise sizing (the blade was slightly in the way):

Next I ripped some 1/2” MDF (I am not a big fan of working with MDF – health wise, but I do have some, and will rarely use it for jigs) to closely match the width of the ply-pattern, and cut it to length.

If you want, you can use a jigsaw and cut the MDF square to the insert size as close as you can to relieve the extra work from the router (next step).

I glued the ply-pattern on top of the MDF block, and with a trim-bit in my router table shaped the MDF to the exact insert size and shape.

Next, I used a straight-cut bit and trimmed the bottom face of the insert by 1/8” – this may vary depending on your saw,and your insert material (the saw lip – where the insert is being held – is 3/8” deep, and I was using 1/2” material). I found that raising the bit up, and holding the insert upright against the fence and protruding the bit 1/8” from the fence gave me cleaner more controlled cut (and also enabled me a deeper cut) as opposed to laying the insert flat on the table and having the bit extend 1/8” above the table.

Last step I cut a 3/4” hole in the front right side (away from the blade) to use as a finger hole to be able to pull the insert up and out of the saw (I drilled mine at a slight angle, but a straight hole would do just fine). I then placed the insert into the saw. moved the fence over the right side of the insert and locked it down. took a long board, and placed it over the left side of the insert (to the left of where the blade is) and clamped it down on both edges of the table. This will hold the insert in place. I then started the saw,and slowly raised the blade up through the insert. and Voila! – Zero-clearance inserts at almost $0 cost.

I made 3 at the same time – might as well. and labeled the bottom of the insert with the ANGLE and BLADE MODEL so that I’ll know to which setting it was made for.

hope this helps…

-- ㊍ When in doubt - There is no doubt - Go the safer route.

17 comments so far

View Callum Kendall's profile

Callum Kendall

1918 posts in 4778 days

#1 posted 07-06-2008 07:04 PM

Great job!

Thanks for the post


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View Keith Benson's profile

Keith Benson

1 post in 4693 days

#2 posted 07-06-2008 08:16 PM

Thanks – pics always help!


-- Bee Sting Honey - So Good . . . It Hurts!

View TedM's profile


2002 posts in 4807 days

#3 posted 07-07-2008 12:09 AM

Cool! Thanks for the how-to!

-- I'm a wood magician... I can turn fine lumber into firewood before your very eyes! - Please visit and sign up for my project updates!

View sawneck's profile


49 posts in 4229 days

#4 posted 10-06-2009 04:27 PM

Great post..One question I have is how did you create the Riving knife hole?

View PurpLev's profile


8652 posts in 4723 days

#5 posted 10-06-2009 04:40 PM

sawneck – I used a jigsaw, and followed the opening made by the tablesaw-blade to make the opening for the riving knife. you could also use a hand saw, and files (to clean up the cut and widen it up)

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View MattOD's profile


4 posts in 3733 days

#6 posted 02-15-2011 05:43 AM

I always enjoy reading your articles. Of particular importance is the simple directions and solutions that you provide.

-- Matt -

View mxrdrver's profile


38 posts in 3737 days

#7 posted 02-18-2011 04:35 AM

I made my own out of 1/2” birch plywood. One regular one and another for dadoes.

View rjoakwood's profile


4 posts in 3604 days

#8 posted 06-24-2011 07:59 AM

Great job there and thanks mxrdrver for posting your pictures.

-- Richard -

View Lumberpunk's profile


334 posts in 3412 days

#9 posted 01-13-2012 09:00 AM

love this made mine today!

-- If someone tells you you have enough tools and don't need any more, stop talking to them, you don't need that kind of negativity in your life.

View Roco54's profile


18 posts in 3442 days

#10 posted 01-30-2012 01:04 AM

I have bought my Bosch 4100-09 and assembled this w/e. What a beauty! its well made and everything fits together perfectly. I paired it with a Freud LU87R thin kerf blade and the quality of cut is amazing. I ordered a factory Zero Clearence insert (Bosch TS1005) and this insert was a disapointment. It is made of plastic and the midle portion is flimsy. If I level the extremities to the table, the midle rises above the table and when I start the saw the blade rubs against the side of the insert and makes a unpleasant screaching noise. Based on the this review I am going to make my own inserts. Thanks for the review and comments. It is really good to come to LJ and get unbiased and personal opinion about so many issues we come across with our woodworking adventures.

-- Life is what we make of it

View crazybrit's profile


9 posts in 3069 days

#11 posted 12-09-2012 07:29 PM

Purplev. Interesting post. Any chance you can rehost your pictures since is no more. Thanks!

View PurpLev's profile


8652 posts in 4723 days

#12 posted 12-11-2012 05:52 AM

post updated with photos fixed.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View Shelha's profile


2 posts in 3019 days

#13 posted 01-29-2013 01:30 AM

Hello PurpLev and mxrdrver,

I just finished making my own insert for the Bosch 4100-09 and in order to raise the blade all the way up, you need to account for the riving knife, the base of the riving knife, and the middle bearing holding the blade. My question to either one of you is, did any of you made your inserts to allow the blade to be raised all the way up? I am just curious.

I also used 1/2” MDF and with the router I removed the material that prevented the blade from going all the way up, the only thing I have left to do is install some screws so I can level the insert just like mxrdrver did on his.

Your posts and pictures were very helpful to me, thank you for sharing!

-- Woodworker novice!

View PurpLev's profile


8652 posts in 4723 days

#14 posted 01-29-2013 02:25 PM

Shelha: as you can see from my photos I ripped the inserts on the underside before using them. this allowed the blade and riving knife to be fully raised as far as I could tell (I no longer have this saw to confirm). but that is a good point if you need the blade raised all the way up.

While on the subject, it got me thinking – I don’t believe I ever needed to raise the blade all the way up. it is usually at the 1/4” – 1-1/2” range

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View Shelha's profile


2 posts in 3019 days

#15 posted 01-29-2013 08:23 PM


Thank you very much for responding! You are absolutely right about having to raise the blade all the way up, my rational was if at one point you needed to do so you had it covered, but chances are you may never need to.

One of the things that was really annoying when I was making the insert, was the fact that between the left supporters of the insert there is a long support that sits much higher, it was a pain to overcome the obstacle because you could not just remove the material evenly, I had to make a deeper cut to make the insert fit. I watched other videos of people making inserts and not one had this issue. (Maybe is just my saw model).

Again, thank you for responding!

-- Woodworker novice!

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