Zero Clearance Throat Plate Inserts

[Neil Bosdet]

I had an epiphany yesterday I thought I would share with this group as it may be very useful to many of you. I have a large project I'm starting for a client and have been tuning up my tools. In the process of replacing zero clearance throat plates on my saws and SCMS I was looking for options on my Saw Stop cabinet saw. I had checked out this article:

http:// www.woodcentral.com/cgi-bin/readarticle.pl?dir=shop&file=articles_893.shtml

(See Ken's note below to make the link work).

It looked like a fair amount of work but a good idea. The problem with Saw Stop is their throat plates are a little on the complicated side with many cut-outs on the bottom side for various clearances. The zci's for the Saw Stop saws are terrific but expensive at $40+.

The epiphany was that the Saw Stops zci's are made of phenolic material. Instead of machining a new throat plate, simply groove out my current plate like the article above. This was a piece of cake. I had it grooved out and 12 maple inserts cut and fit in less than an hour. IMHO this is an excellent solution for Saw Stop saws and any saw that you can source a phenolic zero clearance plate.

191430191431191432

[Neil Brooks]

On that subject ....

I buy "plastic" cutting boards, at Wally World.

They're made from UHMW, machine easily, and -- relative to "proper" UHMW or ZCI's -- cheap, cheap, cheap.

Yours is a good idea, though !

[johnny means]

I'm curious as to why one would need to switch to a new one on a regular basis.

[Neil Bosdet]

My idea saves a lot of time in the future as making the inserts is very fast compared to making the entire throat plate.

[Neil Bosdet]

I'm curious as to why one would need to switch to a new one on a regular basis.

I find they get messed up with angle cuts or switching back and forth from think kerf to reg. The biggest is dadoes. They don't last very long unless you're continually doing exactly the same cut or increasing size. Eventually you need a new one or get poor results.

[JohnT Fitzgerald]

I'm curious as to why one would need to switch to a new one on a regular basis.

Sometimes they get a little chewed up (blade deflection?) and if you cut at an angle it can widen the kerf slot. I like this idea - make one for a pure 90* cut and keep the stock insert for any angled cuts. This is also a great method for making a reusable zci for dado cuts of different widths.

[Neil Bosdet]

Admin pulled my link to the article I wanted those interested to see. I violated (without realizing) the policies here. My suggestion doesn't make a ton of sense without it. PM me for the link.

[Neil Brooks]

It's my understanding that you can't put a direct link, but you can modify the link and include it, if it looks ... like ... this:

www[dot]sawmillcreek[dot]org

I think Keith -- the site owner -- doesn't want to make it too easy for people to click over to other sites -- particularly commercial sites, or those "in competition" with this one.

Which I understand.

Ken: please correct me if I have that wrong.

[Ken Fitzgerald]

I reinserted the link and placed an extra space between // www.

If you copy and paste the link and remove the extra space, the link should work.....



or go go Woodcentral.com....select "articles"....selected "Shop Topics"....then select "Replaceable Insert Throat Plate".

[Neil Bosdet]

Thank you Ken!

[Jim O'Dell]

Nice work Neil! I made one using Corian for the Ridgid contractor saw. Problem is I used all the Corian I had, and now need to make one for the newer Griz saw. Jim.

[Norman Hitt]

Neil, I'm curious about how the phenolic was to route. I have routed aluminum a few times but not phenolic, however I have drilled both aluminum and phenolic, and "Some" of the phenolic was extremely hard to drill. Having seen and used several different kinds of phenolic used in different applications, I realize they are not all equal in ease of workability, so that is why I am curious, as I have debated making one out of aluminum for quite a while but the phenolic should be more temperature stable than aluminum.

[Neil Bosdet]

Neil, I'm curious about how the phenolic was to route. I have routed aluminum a few times but not phenolic, however I have drilled both aluminum and phenolic, and "Some" of the phenolic was extremely hard to drill. Having seen and used several different kinds of phenolic used in different applications, I realize they are not all equal in ease of workability, so that is why I am curious, as I have debated making one out of aluminum for quite a while but the phenolic should be more temperature stable than aluminum.

The phenolic worked like very hard MDF. It was very workable and straight forward. However, the edges on the top on the plate where I dovetailed the 14 degree sides were/are very sharp. I have 3 bleeder cuts on my fingers that I didn't realize I got.

[Norman Hitt]

Thanks for the reply, Neil. I can certainly understand the sharp edges, because when I had to slightly adjust the holes in a predrilled phenolic router plate to center the router over the PC style inlay bushiing cutout, the top edge of the large countersunk holes for the mounting screw insets were sharp also. I had to use a large countersink bit to ease the edges, (after I noticed I was dripping RED on the plate from one of my fingers while starting a screw to mount the router).:rolleyes:

[Lee Schierer]

I had an epiphany yesterday I thought I would share with this group as it may be very useful to many of you. I have a large project I'm starting for a client and have been tuning up my tools. In the process of replacing zero clearance throat plates on my saws and SCMS I was looking for options on my Saw Stop cabinet saw. I had checked out this article:

http:// www.woodcentral.com/cgi-bin/readarticle.pl?dir=shop&file=articles_893.shtml

(See Ken's note below to make the link work).

It looked like a fair amount of work but a good idea. The problem with Saw Stop is their throat plates are a little on the complicated side with many cut-outs on the bottom side for various clearances. The zci's for the Saw Stop saws are terrific but expensive at $40+.

The epiphany was that the Saw Stops zci's are made of phenolic material. Instead of machining a new throat plate, simply groove out my current plate like the article above. This was a piece of cake. I had it grooved out and 12 maple inserts cut and fit in less than an hour. IMHO this is an excellent solution for Saw Stop saws and any saw that you can source a phenolic zero clearance plate.

191430191431191432

I had an aluminum insert made for my craftsman TS a few years ago by a friend. It has a slip in replaceable piece of wood similar to the what you did; however, I tapered the sides of my slot with a dovetail bit so the insert is held down by the throat plate and completely captive once the plate is in place on the table.

I find that my inserts wear from the chips that try to break free along the edge of the cut or by the sawdust. In any event replacements are made from scrap and only take a few minutes to make a dozen or more. I made a large opening in my aluminum plate so I can also use it for zero clearance on dado cuts.

[Neil Bosdet]

I had an aluminum insert made for my craftsman TS a few years ago by a friend. It has a slip in replaceable piece of wood similar to the what you did; however, I tapered the sides of my slot with a dovetail bit so the insert is held down by the throat plate and completely captive once the plate is in place on the table.

I guess I should have put more info in my post. I expected people to read the article that I copied from. I too used a 14 degree dovetail bit on my edges to retain the disposable insert.

[Mike OMelia]

This is a great idea. And as soon as I can figure out who carries phenolic inserts for my Jet Super Saw, I will make one. My current insert is made of cast metal. Not going to touch that one.

Thanks for sharing that!

Can you see your process working with this insert? http://www.amazon.com/gp/aw/d/B0002897MW/ref=redir_mdp_mobile/182-6736678-8065767


Mike

[Noah Katz]

the phenolic should be more temperature stable than aluminum.

That didn't sound right, as all plastics have a much higher CTE than even high expansion metals like aluminum, though the reinforcement will lower it.

I looked it up in my materials reference and the ones listed were all in the range of aluminum, so better than I thought but worse than you thought :)

[Neil Bosdet]

This is a great idea. Can you see your process working with this insert? http://www.amazon.com/gp/aw/d/B0002897MW/ref=redir_mdp_mobile/182-6736678-8065767


Mike

Yes. It looks ideal. Very similar situation to what I had with lots of relief cuts on the underside which makes this idea work so well.

[Mike OMelia]

So, mill out a slot using a dovetail type bit, keep much of the undercarriage stuff as structural support, the angle of the slot edges serve to hold the wood insert in
Place. Round the end to match curvature. Have I a good understanding?

Mike

[Norman Hitt]

That didn't sound right, as all plastics have a much higher CTE than even high expansion metals like aluminum, though the reinforcement will lower it.

I looked it up in my materials reference and the ones listed were all in the range of aluminum, so better than I thought but worse than you thought :)

Hmmmmm, guess I 'forgot' to NEVER assume anything, eh?:o:D I guess the assumption was because I have noticed some aluminum Items expanding on occasion, but never had noticed any phenolic items doing that. I guess they could have, but in their application it wasn't noticeable to me. Not all, but most of my experience has been with Aircraft Quality linen impregnated phenolic used for mounting spacer blocks and insulators, and the type used for older electrical ckt boards and mounting insulators. I do have a couple of solid phenolic router plates with no impregnation and I don't know if the chemistry of that phenolic is the same as the others or not.
Interesting question No less, and thanks for your response.

I have had or used a few Saws that came with Inserts that fit pretty well, but more that were a sloppy fit and or warped, (which I hate). I once made 3 out of HDPE, but they all warped/sagged and 2 of them bowed up like Borg lumber after a while. Since my shop gets VERY hot in the summer, and a short time of very cold in the winter, I just want a material that I can get a snug fit that won't get tight or loose with the change of the seasons. :confused:

[Neil Bosdet]

So, mill out a slot using a dovetail type bit, keep much of the undercarriage stuff as structural support, the angle of the slot edges serve to hold the wood insert in
Place. Round the end to match curvature. Have I a good understanding? Mike

Yes. The depth you make your insert is arbitrary. I made mine about 1/4" thick x 1 3/4" wide. I hogged out the bulk of material with a 1/2" carbide spiral upcut bit. Then I put in the 14 degree dovetail bit and increased the depth a smidge. Grooved the edges (wider) and passed over the main area to smooth out the bottom of the finish.

[Mike OMelia]

Yes, I figured that about the major hogging, and finishing with the 14 deg bit. Just wanted to make sure that the depth of the cut was intended to be supported by the stuff underneath.

Again, great idea.

Mike

[Mike OMelia]

Is this concept the same as the Betterly Tru Cut system?

[Rick Lizek]

Is this concept the same as the Betterly Tru Cut system?

It's actually based on the Wood Dynamics system which came before the Betterly Insert. The WD and dovetailed insert was the best ZCI designed but was too pricey and or not marketed well enough. The WD with the dovetailed insert was quicker to swap inserts and better in the long run.

I am amazed at how some folks think having one ZCI is all you need. We would always make up a couple dozen at a time so we would have them for dado blades, moulding heads and such. The idea is to continually swap them out as they wear so one puts the next compatible size in the appropriate application.

One can also fab up a dovetailed insert holder from pieces of plywood, phenolic or what ever instead of a solid piece. The limiting factor is creativity and resources at hand. The WD inser sold for around $125 and was $50 better in cost than the Betterly insert.

[Mike OMelia]

I think I will go the inexpensive phenolic route. The Betterly is expensive, and so are the inserts. One other question: before routing out the slot, should I run the blade up through the ZCI?

[Neil Bosdet]

I don't know why it would matter either way. I don't think I'd bother myself. If you're insert is new you could use it as is for a while and make up the inserts when it gets worn.

[george wilson]

I don't know why the Saw Stop throat plate needed to be made so complicated. I made one for the SS I bought for work. Being a machinist I was able to do so. But it did take a milling machine. Would be MUCH nicer if their throat plates were like most others. Maybe its done so you are forced to buy their stuff? I like just being able to make one out of plywood for my 1964 Dewalt/Clausing table saw.

The dovetailed routed wood replacement insert sounds like a good idea.

[Noah Katz]

I just want a material that I can get a snug fit that won't get tight or loose with the change of the seasons. :confused:

Put in a ball plunger or two on the side to spring load it.

I just did a quick calculation to see how much clearance should be allowed; assuming a 20" long throat plate, the differential expansion between cast iron and aluminum for a 25 C temp change is .006".

[Neil Bosdet]

I don't know why the Saw Stop throat plate needed to be made so complicated.

Me too. Some of it seems unnecessary but I think it's to allow the blade to get as high as possible and to allow the blade to angle easily.

[Mike OMelia]

I finally got my Phenolic ZCI in and I need to know how deep you went with the slot. Also, would you reccomend this for a dado blade?

Mike

[Neil Bosdet]

I finally got my Phenolic ZCI in and I need to know how deep you went with the slot. Also, would you reccomend this for a dado blade?

Mike

Depth is up to you. I went about a 1/4". Check the thickness of the ZCI that you bought. Definitely use this for both set ups, standard and dado. That's one of the big plusses for this as dado inserts get replaced often when you mix up your widths of dados.

[Mike OMelia]

About the dado... I guess I am trying to figure the right slot width to accomodate it (as well as saw blades)

Mike

[Neil Bosdet]

About the dado... I guess I am trying to figure the right slot width to accomodate it (as well as saw blades)

Mike

Yup. Again, the width is up to you. I made sure a 3/4" dado was accomodated and roughly centered and allowed about 3/8" to each side (going from memory).

[Mike OMelia]

I mean, I could figure this by measuring from arbor base, and biggest dado width, right?

[Neil Bosdet]

Yup. Again, the width is up to you. I made sure a 3/4" dado was accomodated and roughly centered and allowed about 3/8" to each side (going from memory).

Sure, but just use your current plate to base it from. Keep it simple.

[McKay Sleight]

I have a commercial plate that looks exactly like the throat plate above made by Wood Dynamics. I believe that they are out of business because I have not been able to reach them for a number of years. I have 0 clearance inserts for every angle and dado size that I use. I keep them close by and I change them out at least 1-2 times a day. I mark the underneath side so that I can quickly change them. This and good blade makes a huge difference when making cuts.