Looking for temporary use of a zero clearance throat plate for 3D modeling

[jlmeredith]

This is the photo I am using to model the lower portion of the plate since I have not been able to secure a sample. I will do my best to create the same structure in the final part.



Here is the current state. I will add some cut outs for the arbor and add in the ribbing to give the plate more mass. I will also be generating a version that has holes pre-placed for a Microjig Splitter attachment.

Getting there!

[jlmeredith]

How about an interlocking joint like jigsaw puzzle? Overlapping perhaps for vertical alignment.

I am using a simple dovetail for the prototyping right now, but long term, I will use a scarf joint that will will ensure a perfectly flat surface for those that opt for printing in two pieces. I may also make a version that has just the blade cut out portion removable. This would allow one to print a solid outer section and then change out the Zero Clearance portion apart from the frame.

[LCHIEN]

Very Cool! I see a lot of thinking has gone into this. More thinking than I have done. Good job!
I also like the idea that you hollowed out the underside some. I know that reduces material use and solves the jamming the blade and washers problem. But that you kept a lip around the area to stiffen the whole plate.

My ZCTP has suffered a lot of abuse through the years and I have thought about replacing it.
The three hole pattern as I suggested is in thin material and the use of countersunk flat head screws has made overzealous tightening break out the edges.
The poor plate has been jammed on much more than one occasion by attempting to bevel tilt the blade without changing to the metal OEM throat plate only to hear all the parts screaming in protest and the poor plate twisting in ways it was not meant to.
Finally, and I don't think there's much you can do about this, is that the thin portion at the back has cracked where the cut has been made all the way back to accommodate the riving knife. I can't think of any way to reinforce that part which is like .080 thick and about half an inch wide. Of course the original OEM metal throat plate is split in this area so maybe its not a big deal.

I sure would be happy to see that I could get a couple of printed blanks. Thank you for sharing.

[jlmeredith]

I thought others might appreciate seeing the iterations that I have been through to get to this point.

Today, I will print a new version that will account for the arbor/washer cut outs in the full height position as well as adding some additional support ribbing in the areas where the blade does not pass up through or interfere with the plate.

I think I will also need to make a small additional change to address the blade assembly on the back side of the saw making sure that there is not a collision point where the carriage assembly moves up toward the plate.

LCHIEN - I will be adding a version with a cut out for the factory splitter and I think because this is 3D printed, I can make it so that there is more support there hopefully. Like I indicated though above, I am also making a version that will have holes for the Microjig Splitter. I will be sure you get a couple of these when they are completed! Thank you for your encouragement and feedback/help!

This is just a photo of several iterations where you can see the progression of my work. Starting on the right, I modeled the insert for size, then adjustments for holes and thickness, then the version that had some print issues when making the deeper version, then the final version that I have confirmed clears the blade and arbor assembly.

[jlmeredith]

I have uploaded this first version for others to take a look at or print if they would like. This does not account for several changes listed in my last comment:

https://thangs.com/designer/jlmeredi...urce=All+Files

[d_meister]

The content isn't available at the link location. Maybe pending admin check?

We couldn't find the page you're looking for. Sorry!

EDIT: It's working, now.

[d_meister]

For your consideration, here is an aftermarket ZCTP I bought years ago machined from solid Starboard type HDPE. The original material thickness was 1/2".
The infill % setting can maybe provide the rigidity desired?.

[jlmeredith]

For your consideration, here is an aftermarket ZCTP I bought years ago machined from solid Starboard type HDPE. The original material thickness was 1/2".
The infill % setting can maybe provide the rigidity desired?.

Thank you for the example @d_meister!

Once I have completed all of the prototyping, I will likely print this a near 100% infill, assuming that this does not create an issue with flatness. Unfortunately, solid printed parts can sometimes warp or bend. For anything I print for others, I will be using either PLA+ or ASA. I need to see how each material reacts to being cut through and if there will be any issues with tearout or weakening of the design. Regarding the thickness, I have determined that up to .625" of thickness should clear any blade or read splitter assembly. If I can make it thicker to give things more support, I will probably do so.

[d_meister]

I've been thinking about cutting a boss into the ZCTP I showed with a router to lay in 1/8" plywood replaceable inserts, maybe with sufficient depth for carpet tape to hold the ply inserts, or simply screw down. Incorporating something like that into your design could help join the two halves and eliminate the concern about infill voids at the blade penetration point. Maybe allow for dado blades, too? Maybe good place for melt-in nut inserts?

[jlmeredith]

d_meister - I mentioned a similar approach in my above comment, but that would be something to address after I have the actual plate completed. I could see having a universal base with replaceable inserts, as you mentioned, that would allow for different blade kerfs and designs (dato set). I will keep this in mind going forward for sure!

I am using a simple dovetail for the prototyping right now, but long term, I will use a scarf joint that will will ensure a perfectly flat surface for those that opt for printing in two pieces. I may also make a version that has just the blade cut out portion removable. This would allow one to print a solid outer section and then change out the Zero Clearance portion apart from the frame.

[jlmeredith]

New version with under grid, cutouts for arbor and washers as well as a full thickness top plate with no voids. I will mount this version and attempt a test to create the blade slot. I did make the walls much more thick than the original as the material will not be as dense and this will provide additional rigidity. I may shrink them down after I test.

[LCHIEN]

I think it was a good idea that you added the grid for rigidity. I was wondering about making a comment to that effect but you obviously had it in mind. Not sure how flat it will stay and its rigidity as I don't have any experience with these materials.
Fun watching it take shape and evolve!

Loring

[jlmeredith]

Photos below

So the last plate I sent was a flawed print, as I incorrectly placed the cutout for the arbor too far to the back. I transposed something, not sure.

Anyway, I adjusted the location, took .2mm off of the top plate so that is just a thousandth lower than the table. Printed and seats perfectly.

I just have a small problem. I do not have any self taping screws and that is what I think originally came with the zero plate.

If anyone happens to have the specs on this, let me know. I looked in the manual and all it says is: "Thread cutting screw - 1 in. (1) (For use with BT3000)".

Ultimately, I will glue this last sample up and hot glue the insert down for testing. I could use my tap and die set, but looking at the raw holes, they appear to not have a flat interior, which tells me they used some kind of special screw.

Anyway here are the latest photos and comments

This is was the first failed attempt with the new grid, but it was easy to correct and reprint.

This is the plate assembled and placed upside down. Note that the arbor cut out is on the opposite side here but correct when flipped.

I will likely revise this to not have the cut out all the way to the outer wall that faces the right side of the saw. I did this mostly to check alignment with the arbor wrench cutout and to verify placement. I can adjust the inside cutouts as needed in Shapr3D. ​​​​

Here I have removed the front section of the plate and I am verifying that the location of the zero clearance cutout is between two ridged walls. While it is hard to see in this photo, plate area directly above where the blade will cut through is a solid sheet of plastic about 10 layers thick at .28mm layer heights. It is very dense and about 25-30% thicker than the rest of the top surface of the plate. I believe this should be as good or better than the factory plate, will make adding the MicroJib Splitter easier and possible be safer with more material that would have to break away if it ever splinters or separates. That will the real test of this little journey. If that does become an issue, I will just make a resin mold and mold them, lol.

I used a slightly different version of the dovetail join I have been using. This time I angled it at about 35 degrees and put some additional taper on the dovetail. In spite of not having a lot of material to bite on, it is surprisingly stiff with no glue. I would not cut with it like this as the are likely to come apart but with some CA glue, I think it will be fine once the relief cut is made. ​​​​For those who are wondering, the joint is made in Bambu Labs slicer. You can directly cut the part in two pieces with all kinds of variables and adjustments. It has been fun experimenting with this through out the project.

This is what the joint looks like up close. Very clean!

[LCHIEN]

you don't need self tapping screws, just use a 10-24 tap.
from my FAQ



I believe that the four-hole set is untapped from the factory, The table top is aluminum and should thread pretty easily. Use some cutting oil or practically, any machine oil to help cut the cuttings, change direction while cutting frequently to clear the threads, if you have not used a tap before.
if you don't have my FAQ here is the link
https://www.sawdustzone.org/forum/di...sked-questions

It's looking great!

[jlmeredith]

Thank you! I should have thought to check your FAQ! I have been so focused on getting the design right I forgot the detail! lol - likely have the bolts you mentioned or I can grab in the morning from the local hardware!

[LCHIEN]

This picture brings up one possible issue. If a partial full stack (3/4 or 13/16") dado is used and raised to maximum elevation the right blade washer will hit the bottom of the plate.

Maybe its not an issue... I have the metal dado plate I used when cutting large wide deep dadoes anyway. I only use my ZCTP cut for dados with smaller, less height dadoes - and its usually not zero clearance... since dadoes have a near infinite range of widths.

I guess its not something worth worrying about at this point.

[jlmeredith]

Good photo magic btw! lol

[jlmeredith]

This picture brings up one possible issue. If a partial full stack (3/4 or 13/16") dado is used and raised to maximum elevation the right blade washer will hit the bottom of the plate.

Maybe its not an issue... I have the metal dado plate I used when cutting large wide deep dadoes anyway. I only use my ZCTP cut for dados with smaller, less height dadoes - and its usually not zero clearance... since dadoes have a near infinite range of widths.

I guess its not something worth worrying about at this point.

Unfortunately this shot is not best at showing the actual clearance at the arbor as this is the back half of the plate just showing general center for the zero clearance slot.

There is a good bit of material I just chopped out at that point of the plate where the arbor intersects.

Below is a better photo. Forgive the crude on screen drawing, but my plan after validating things is to close up the area in yellow and remove some of the inner support structure. I figured I can just cut through whatever plastic initiall and then see how that shakes out for rubbing and clearance.

Your point though is valid and I should account for when that washer is to the inside of the stack of spacers. I had not seen that configuration before (never used a dado set lol).

I should also look at the contour of the cut out as I do not think it is the right diameter or something in my print. It looks way smaller than the washer. I will know in the morning.

I am currently using shims from Tim Hall to replace the old busted ones and giving everything a good lube. I think in its prior life it may has sat outside or under an awning for a short while. Just enough to put a fine layer of rust on everything, lol.

Thanks for the feedback. This has been a fun project to share! Your reference material has been invaluable!

[d_meister]

I downloaded your original release and cut it in half in software in order to test print it in PLA. It printed properly, and the fit would be excellent, but the ends did curl up off the plate during printing. From experience, I don't think fighting that battle on the adhesion front would be fruitful, so an enclosure is going to be necessary in my environment. Ambient was about 72° F with no noticeable draft, but the printer is near a double-paned window, so will always have some convection flow.
Even though there was a small lift due to the slight curl, I noted that I needed to adjust the location of the 24 tooth Diablo rip blade so that there wasn't tooth interference with the underside. The thickness of the plate in the area of the blade will be critical in the final iteration, as securing the plate with teeth in contact could grenade belts if in marginal condition or stall the motor.
You're doing a great job with the project, and I was quite impressed with the original! Thank You!

[dbhost]

If your prints are curling up, drop your parts cooling fan speed, to potentially turning it off. PLA likes to curl as much as PETG likes to string. I am trying to run a batch of miter fence ends out of PETG and at least it is only the supports that are doing it, but man is it stringy...