# Reducing bottom side tear-out on plywood? **URL:** \ **Category:** General Chat\ **Created:** [January 1, 2024, 12:41am UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802 "2024-01-01T00:41:58Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![JtheB](https://avatars.discourse-cdn.com/v4/letter/j/b77776/32.png) [@JtheB](https://forum.avidcnc.com/u/JtheB)\ **Post date:** [January 1, 2024, 12:41am UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/1 "2024-01-01T00:41:58Z")
I mainly cut Baltic birch plywood and would really like to develop reliable strategy for reducing tear-out on the bottom side of the material. By “reliable” I mean will be mostly successful even when a tool isn’t “factory sharp”. Feeds & speeds don’t ever stray far from each brand’s recommendations. I have a vacuum system to hold down full 4x8 sheets but the waste board has scars that leave briefly unsupported traverses during final passes. But this shouldn’t be a huge issue I’d think… Drilling - Surprisingly even Amana Brad Point bits leave bottom side tear-out. Increased rpm + decreased plunge rates help but those are maxed to either end of their respective scales as dictated by the brand. A partial drill with a final peck through the bottom side laminate with an up-cut endmill still seems problematic. Standard Cuts - I’ve tried offsetting the outside toolpath by 1/16" leaving that materials for a final pass with a compression bit with some success, but lining up all the tabs for those parallel (adjacent) cut path will be a bear on some of the more complex pieces… Is this the best approach in the end? ---
**Author:** ![JtheB](https://avatars.discourse-cdn.com/v4/letter/j/b77776/32.png) [@JtheB](https://forum.avidcnc.com/u/JtheB)\ **Post date:** [January 1, 2024, 5:27pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/2 "2024-01-01T17:27:17Z")
And I’ve been using 1/4 bits to cut out shapes in 3/4" BB ply in effort to minimize material waste. Would using 3/8" bits have any advantages as far as bottom side tear-out? - like the cutting edge having a slightly reduced angle of attack due to the increased radius… ? ---
**Author:** ![sehast](https://avatars.discourse-cdn.com/v4/letter/s/2bfe46/32.png) [@sehast](https://forum.avidcnc.com/u/sehast)\ **Post date:** [January 1, 2024, 11:51pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/3 "2024-01-01T23:51:40Z")
I use this bit to cut 3/4" BB in a single pass with great success. Watch the video link provided in the description. > **[1/8" Compression Bit for cnc to cut plywood high quality Made in Korea | eBay](https://www.ebay.com/itm/264526762192)** > > Great for cutting plywood ,PVC and wood in general. 1/8" shank 3.175mm. The cutting part is about 7/8". ---
**Author:** ![JtheB](https://avatars.discourse-cdn.com/v4/letter/j/b77776/32.png) [@JtheB](https://forum.avidcnc.com/u/JtheB)\ **Post date:** [January 2, 2024, 12:57pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/4 "2024-01-02T12:57:08Z")
That’s pretty impressive… Seems using no dust vac eliminates the need for tabs since the chips keep the piece nestled. The bit doesn’t overheat? ---
**Author:** ![sehast](https://avatars.discourse-cdn.com/v4/letter/s/2bfe46/32.png) [@sehast](https://forum.avidcnc.com/u/sehast)\ **Post date:** [January 2, 2024, 4:06pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/5 "2024-01-02T16:06:18Z")
I run it at 18000 RPM and 30-60 IPM. I haven’t noticed any overheating but I do clean it frequently especially after cutting MDF. Its not going to last forever without getting dull but at this low price I always have a few on hand if one gets dull enough to break. The only one I broke was when I tried to cut 3/4" HDPE which was a really dumb idea even with a brand new sharp bit. The one I used had over a year of use on it so the increased density of the HDPE quickly did it in. ---
**Author:** ![Hack](https://avatars.discourse-cdn.com/v4/letter/h/839c29/32.png) [@Hack](https://forum.avidcnc.com/u/Hack)\ **Post date:** [January 4, 2024, 12:36pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/6 "2024-01-04T12:36:02Z")
I run a vacuum table and I cut quite a bit of 2 sided UV coated maple plywood and the tear out from routing is minimal to non-existent. I use the Whiteside 2602 compression bits in 1/4" diameter. 300 ipm 2 passes (.375" DOC). I feel this is a bit conservative, but the bits last and sound great at this setting. I will usually cut .010" - .015" into the spoil board to be sure I do not leave any onion skin which tears way to easy. Drilling on the other hand, I have found nothing that works. Brad point bits just splinter the veneer on the backside. I have gotten to the point where I do not drill all the way through or if I have to, route the hole instead of drilling if finish on the second side is critical. ---
**Author:** ![JtheB](https://avatars.discourse-cdn.com/v4/letter/j/b77776/32.png) [@JtheB](https://forum.avidcnc.com/u/JtheB)\ **Post date:** [January 4, 2024, 1:25pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/7 "2024-01-04T13:25:00Z")
Thank you Hack. All great info. I’ll give your setup a try. And comforting to know I’m not the only one that struggles with drilling. I’m drilling 100+ 6mm & 8mm holes in 3/4 bb plywood per run so cleaning up the bottom side splintering gets tedious. I may try partial drilling and then pocketing the last depth with an 1/8" upcut… ---
**Author:** ![JtheB](https://avatars.discourse-cdn.com/v4/letter/j/b77776/32.png) [@JtheB](https://forum.avidcnc.com/u/JtheB)\ **Post date:** [January 4, 2024, 1:39pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/8 "2024-01-04T13:39:30Z")
> [@Hack](#): > > I use the Whiteside 2602 compression bits in 1/4" diameter. I’m finding this to be a straight trim bit… ? > **[Search: 1 result found for "2602"](https://www.whitesiderouterbits.com/search?q=2602&type=product)** > > Home of Industrial Grade Router Bits & Drilling Tools. Family Owned and Operated. American Owned and Operated. Committed to Quality and a Superb Product Line. Maybe 2100/2102? Regardless, single or double flute? ---
**Author:** ![Hack](https://avatars.discourse-cdn.com/v4/letter/h/839c29/32.png) [@Hack](https://forum.avidcnc.com/u/Hack)\ **Post date:** [January 4, 2024, 7:43pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/9 "2024-01-04T19:43:56Z")
Sorry about that. Yes, it should have said 2102, specifically the UD2102. 2 flute compression bit. ---
**Author:** ![Rapidfire](https://avatars.discourse-cdn.com/v4/letter/r/e68b1a/32.png) [@Rapidfire](https://forum.avidcnc.com/u/Rapidfire)\ **Post date:** [January 6, 2024, 4:10am UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/10 "2024-01-06T04:10:42Z")
Consider the Amana 46170-k (1/4” compression bit). It’s my go to bit for BB ply and haven’t had any tear out on the underside. Runs at 18000rpm & 100-150 ipm. Use a hurricane vac system for holdown with a phenolic plenum board and LDF spoilboard. ---
**Author:** ![JtheB](https://avatars.discourse-cdn.com/v4/letter/j/b77776/32.png) [@JtheB](https://forum.avidcnc.com/u/JtheB)\ **Post date:** [January 6, 2024, 10:37pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/11 "2024-01-06T22:37:25Z")
> [@Rapidfire](#): > > Consider the Amana 46170-k (1/4” compression bit). It’s my go to bit for BB ply and haven’t had any tear out on the underside. Runs at 18000rpm & 100-150 ipm. 1. You’re running single pass in 3/4’ BB ply? 2. Conventional cut, yes? 3. What difference do you notice between 100 ipm and 150 ipm? ---
**Author:** ![Aerojunkie](https://avatars.discourse-cdn.com/v4/letter/a/77aa72/32.png) [@Aerojunkie](https://forum.avidcnc.com/u/Aerojunkie)\ **Post date:** [January 6, 2024, 10:56pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/12 "2024-01-06T22:56:27Z")
What router or spindle are you running? ---
**Author:** ![TwigStudio](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/twigstudio/32/3152_2.png) [@TwigStudio](https://forum.avidcnc.com/u/TwigStudio)\ **Post date:** [January 6, 2024, 10:56pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/13 "2024-01-06T22:56:43Z")
The material I use for my bread and butter work is 9mm BB. I use the Whiteside 3/8" compression bit with 3/8" shank. I run it at 18000RPM at 200 IPM. I don’t ever get any pullout unless there are voids or other defects in the material… I don’t have vacuum hold down but I do use a pretty powerful dust collection system. I need to use tabs to keep the pieces in place. Here’s what the edges look like. ![edge_pic](https://canada1.discourse-cdn.com/flex027/uploads/avidcnc/original/2X/1/16e049b9e45105627a5dc815319175f07fdf9e6b.jpeg) ---
**Author:** ![JtheB](https://avatars.discourse-cdn.com/v4/letter/j/b77776/32.png) [@JtheB](https://forum.avidcnc.com/u/JtheB)\ **Post date:** [January 7, 2024, 12:40am UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/14 "2024-01-07T00:40:59Z")
> [@Aerojunkie](#): > > What router or spindle are you running? A CNC Depot RM30C Basically it’s the new RM40 model in a 3hp version. ---
**Author:** ![JtheB](https://avatars.discourse-cdn.com/v4/letter/j/b77776/32.png) [@JtheB](https://forum.avidcnc.com/u/JtheB)\ **Post date:** [January 7, 2024, 12:53am UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/15 "2024-01-07T00:53:03Z")
Thank you all for the various tool/setting combos. Many of your suggested cutters on the way for trial. DRILLING… I’m often poking 100+ 1/4" & 8mm holes in a single sheet of 3/4" BB ply. It’d be awesome to solve the bottom side splintering issue. Fresh spoilboard for every sheet isn’t realistic for _anyone._ I’m totally cool with multitool strategies. ---
**Author:** ![Rapidfire](https://avatars.discourse-cdn.com/v4/letter/r/e68b1a/32.png) [@Rapidfire](https://forum.avidcnc.com/u/Rapidfire)\ **Post date:** [January 7, 2024, 1:26am UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/16 "2024-01-07T01:26:02Z")
1. 2 passes, 3/8” deep each pass 2. Yes, conventional 3. Not much difference…use the 150ipm on larger cutout pieces and 100ipm on smaller pieces. If mixed and matched, I’ll compromise on 120ipm. ---
**Author:** ![TwigStudio](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/twigstudio/32/3152_2.png) [@TwigStudio](https://forum.avidcnc.com/u/TwigStudio)\ **Post date:** [January 7, 2024, 6:47am UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/17 "2024-01-07T06:47:46Z")
In the same work discussed above there are dozens of holes and pockets per sheet. For the holes I drill with a 3/16" up cut, no pecking, whatever the recommended plunge rate is (50-60 IPM?). I find it best to drill right through, into the spoil board by about 20 thou. For pockets, I use a 3/8" downcut, 18K RPM 200 IPM. the downcut minimizes pull up on the edges and also results in smoother pocket surfaces. The tools and feeds/speeds for these I arrived at very iteratively. ---
**Author:** ![JtheB](https://avatars.discourse-cdn.com/v4/letter/j/b77776/32.png) [@JtheB](https://forum.avidcnc.com/u/JtheB)\ **Post date:** [January 7, 2024, 2:32pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/18 "2024-01-07T14:32:31Z")
> [@TwigStudio](#): > > For the holes I drill with a 3/16" up cut, no pecking Interesting considering most references I’ve encountered consider it a no-no to drill with end mills so I was steered away from this practice early on - perhaps the “rules of thumb” are usually based on metals machining where things are less forgiving? I’ve always wondered how flute count and helix angle might assist in this scenario. I see advantages to increasing and decreased both those variables… with tradeoffs for each choice obviously… ---
**Author:** ![TwigStudio](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/twigstudio/32/3152_2.png) [@TwigStudio](https://forum.avidcnc.com/u/TwigStudio)\ **Post date:** [January 7, 2024, 4:17pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/19 "2024-01-07T16:17:17Z")
Ive had burning of the bit using straight bits to drill. Also, any time i’ve taken a short cut and tried to drill with a compression i,ve had burning. But the upcut bits work fine for me. This is in 3/8" (9mm) material. I’m not sure if it would be any different with 3/4" material. I say Just give it a try. You would want to plunge as fast as you can imagine the bit being able to cut through. I just use that bits plunge rate from the database. If you go too slow it will burn for sure. I don’t want to peck drill if I don’t have to because my production runs on the machine are 88 sheets at a time. That’s why I take the effort to try anything that can save cutting time. Its the same for hold downs, sheet changes, everything! The machining times add up. ---
**Author:** ![JtheB](https://avatars.discourse-cdn.com/v4/letter/j/b77776/32.png) [@JtheB](https://forum.avidcnc.com/u/JtheB)\ **Post date:** [January 7, 2024, 4:31pm UTC](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802/20 "2024-01-07T16:31:57Z")
Thanks Twig I’ll have a go at it. [Next page](https://forum.avidcnc.com/t/reducing-bottom-side-tear-out-on-plywood/2802.md?page=2)