Chips packing the cut

2931 Views 16 Replies 7 Participants Last post by TimPa, Feb 4, 2021

Afish

Discussion Starter · Jan 30, 2021

Hello all, first time poster. I just got my CNC router and was making some cuts in 3/4" Russian birch ply using a 3/16 upcut spiral but even though its an upcut bit Im getting the chips densely packed in the cut. Im following the Amana speeds and feeds 18k RPM, 150ipm, with a cut depth of 1x the diameter of the bit. Since this is my first time Im not sure if this is usual or if I should be trying to adjust the speeds and feeds and if so which way up or down. I have no issue with the cuts but dont want to be prematurely wearing out the bit either. I havent had any breakage yet but the chips cant be helping. I would expect this with a down cut but with a upcut it somewhat surprises me. I am using a 3hp laguna cyclone so Its not a dust collection issue. When the part is done I have to use a pick to loosen up the chips left in the cut. I havent tried a bigger diameter bit so Im not sure if this is just a small bit issue or if Im doing something wrong.

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BalloonEngineer

· #2 · Jan 30, 2021

Are you doing a cut all the way through or just a slot? I find chip packing generally to be advantageous, holding the cutout in place without using tabs. But I use a compression bit to cut Baltic birch, I would expect an upcut to clear a lot more, but not all the chips. Here is an example, using 1/8” bit to cut through 1/2” (12mm) Baltic birch ply, single pass.
Closed Cottage sign

Reactions: 1

difalkner

· #3 · Jan 30, 2021

What was your feed rate on that, Richard? You are definitely cutting faster than I do with a 1/8" bit. When I saw the first pass for Z clearance I thought it was a bit low, and then when it hit the part from the 'A' I knew it was too low.

David

Afish

Discussion Starter · #4 · Jan 30, 2021

4 evenly spaced passes approx. .1772" each pass. Material measured .707 total cut depth was .709"

Afish

Discussion Starter · #5 · Jan 30, 2021

That was impressive cutting that full depth birch ply with a 1/8 cutter at that speed (also interested to know the IPM) makes me think im being a bit of a sissy with my speeds and feeds but this is new to me so Im trying to take it slow at first. I could see the chips being a benefit on full depth cuts but it seems like they would help heat up the bit more when doing multiple passes. The chip holding with no tabs is also impressive. I didnt have that many chips packed in there I would say the kerf was about 50% full but that was more than I expected with an upcut.

BalloonEngineer

· #6 · Jan 30, 2021

difalkner said:
What was your feed rate on that, Richard? You are definitely cutting faster than I do with a 1/8" bit. When I saw the first pass for Z clearance I thought it was a bit low, and then when it hit the part from the 'A' I knew it was too low.

David

That was 100ipm, the Z clearance was .05", both the clearance of collet nut and the clearance between bit and stock look lower in the video than it actually was. It is only hitting the piled up chips. I can't use vacuum much in my temporary shed while I am building my new home/shop, its only 12x16 and doesn't have power, everything is running off extension cords, and I only have so many circuits on the temporary power pole. I have run 1/8" bits up to 200ipm in MDF, but only at 1/8" depth, 150ipm at 1/4" deep. This was a cheap ($5) Hozly compression bit, I have gotten quite good results with them.

Chips cool the bit. If you feel the chips, they are quite warm, the bit is cool enough to touch immediately after the cut. If you make lots of passes and keep recutting the same chips, you may have different results.

Reactions: 1

Pro4824

· #7 · Jan 30, 2021 (Edited)

Nice!

difalkner

· #8 · Jan 31, 2021

BalloonEngineer said:
That was 100ipm

Ok, I cut at 75ipm and occasionally at 100ipm with a 1/8" bit but that just looked faster.

David

BalloonEngineer

· #9 · Jan 31, 2021

difalkner said:
Ok, I cut at 75ipm and occasionally at 100ipm with a 1/8" bit but that just looked faster.

David

75ipm is for single pass cutting .75 material with the 1/8” bits I have have for that. I’ll have to make a video next time I do it. 1/8” bit for cutting 3/4 ply (one pass)

Reactions: 1

MarkJonesRanger

· #10 · Feb 2, 2021

While watching the spindle versus the router I noticed my router cleans out all the slots as the fan from the router blows it all away. A router is good for that over the quiet cool spindle with no fan.. However I did build a dust/noise box over the CNC to contain the dust and noise. I do like it that my router clears the bit as it cuts.

Reactions: 1

ger21

· #11 · Feb 2, 2021

Chips packing in the cut is normal. About the only thing you can do to avoid it is to use compressed air to blow them out, using a nozzle aimed at the tip of the bit.
Some of the newer high end routers have multiple air nozzles, and turn them on and off depending on the direction of cut, for maximum effectiveness.

MarkJonesRanger

· #12 · Feb 3, 2021

Chips don't pack my cuts. It's not normal. GRIN! Router blows the chips clear. The sound box controls the dust and the noise. The windows allow viewing the cutting in action. I can see a whole lot more than the dust boot options that didn't control the dust in the shop. If I did change to a quiet no fan spindle router I would be wanting to add a air hose so I can see what is going on. These things are fun and I have enjoyed making over a hundred projects with it these past 5 months. Started a web page on my shop updates and projects. It's current to date.
Shop update 2019 (tzo.com)

ger21

· #13 · Feb 3, 2021

MarkJonesRanger said:
Chips don't pack my cuts. It's not normal.

Then you're not cutting very fast or very deep. It's not desirable, but it's unavoidable at high speeds and deep cuts, and is worse with smaller bits.

Reactions: 1

MarkJonesRanger

· #14 · Feb 3, 2021

Ok. Your right. I have chips in my slots and pockets. I just don't see them because my Porta cable router blows them away as soon as they are cut. GRIN! If you need video of what I am saying via 1/8" slots or 3/4" wide bits cutting 1/8" to 1/4" at a time cuts I can provide that. I just cut 17 wooden canteen kits and 24 lantern kits out of cedar, walnut, maple, oak and even the pine and fir! No chips in my slots! Again. The box enclosure that fits over my CNC keeps all these chips that are blown out from blowing all over my shop...(the downside of having a router with a fan that blows the chips everywhere). Just saying. I see what your talking about with the cool quiet spindle routers. They indeed have chips in the slots from what I have seen.

TimPa

· #15 · Feb 3, 2021

... with the cool quiet spindle routers. They indeed have chips in the slots from what I have seen.

usually not with decent dust collection...

MarkJonesRanger

· #16 · Feb 3, 2021

Funny thing is I seldom see a CNC with a dust collection boot on them as it covers up the bit as it is cutting. Most say they usually use the dust boot as it is filling their shop up with dust as the video records. My point in this was there is a good and bad point on setups. The quiet spindle routers with no fan blowing down on them have chips in the slots (On video as the boot is most often removed to show what it is doing). While the noisy router is blowing the chips out of the slots and off of most of the table top to the sides of the CNC table allowing one to see what is going on. YET one needs a enclosure to contain the dust and deaden the noise.

I no longer use a dust boot. I have a much cleaner and quieter shop with the enclosure and no dust boot. It took me a few months to get the best option for the money. I would say your right a better dust collection system by throwing money at it would fix that problem as it will for most woodworking issues. I get along fine with a 1 hp delta bag single machine with a dust deputy.

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TimPa

· #17 · Feb 4, 2021

you are right Mark, when the tip of bit extends down lower than the dust boot bristles, and the "cut" is happening below the dust boot, the dc is not being very efficient and i get chip scattering. but when a shorter bit is being used (or the longer bit is getting deeper into the wood) and the cut is happening inside the dust boot, it works very well.

i've learned to insert the bits so where the flutes are just starting at the collet. makes you pay more attention to a bit's cutting length.

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