Poor edge quality

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Rob Davis
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Re: Poor edge quality

Post by Rob Davis »

Jason, excuse me if this seems like 2 elementary questions but here goes: 1) What effect is there if the chip load is too light (i.e. - running FPM too slowly for RPM per chart) as we know too much chip load = overheating, breaking tools, etc but is there a down side for running too slowly other than lost production? perhaps fuzzy edges.....
2) Seems like there should be some factor for material thickness here also as you can cut 1/4" MDF a LOT faster than you can cut 3/4" MDF. Is there a factor for this?
Hated to clutter up the board or highjack the thread with this but maybe I am not alone in my ignorance(?)
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Re: Poor edge quality

Post by Josh Rayburn »

Rob,
Feeding slower will cause more heat and reduce cutter life significantly. I'm no scientist, just my experience. Feeding too fast has never caused problems with tooling life, only cut quality and the deflection issues which are ultimately a problem with edgebanding. Way too fast = broken tool.
Don't know if this helps or not -
jnr
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Neville Bastian
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Re: Poor edge quality

Post by Neville Bastian »

Tooling is a black art. This is hard to come to grips with especially the harder you run some router bits the better they perform and the longer they last? I think we all need to talk to our local Lietz or similar expert with material we are cutting and quality we expect and cost per sheet.
I have said this before but I believe it is too hard to build into control nesting, if you could get a report on the tool life number of meters/feet it has cut with a percentage of materials it has cut it would be a interesting exersise. The comparing of router bits with cost and performance is not a concern in my case of those who run the Thermwood and order replacement tooling. It is for me each month when I sign the cheque. :wall:
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Neville
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Re: Poor edge quality

Post by Kerry Fullington »

We probably need to factor in hold down when calculating which tooling at what feed rate.
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Re: Poor edge quality

Post by Gerry A Brown »

I was away yesterday so I am late replying.

Will
The machine is a 2007 model that is new to us. We purchased it from a leasing company that took it back. We are in southern Alberta & there is not easy access to service here so we are trying to solve these problems in house.

Jason,
I have been in touch with the Panolam rep & this problem is known to them with this core. They suggest another panel with a Pine core or the new Z core product. I have a few sheets of each on order & will post with the outcome. I also spoke with a Vortex rep. My thinking was changing to a bit with more flutes may not be beneficial because you adjust feed rate & spindle RPM to attain the same chip load which = same cuts per inch. The Vortex rep agreed with this thinking & thought the .5" comp I am using is the right tool for the job. I thought a bit with a steeper shear helix would give more up & down force to resist pulling the core apart but the shear angle is the same on all the bits so that is not an option. They do have finishing down-cut bits with 1 flute that are said to eliminate any lip caused by comp cutters but these are used for a light second pass. I was surprised to see that the plunge ramp in does not happen outside of the finished edge. Plunging a bit that is up-cut even if only the bottom .25" results in chipping on the face. The router re cuts the ramp-in section so if the ramp-in was outside of the finish edge that would clean-up the chipping that occurs on the ramp-in. It is good to hear that the double pass is on the wishlist. Is the ramp-in outside finish edge option also on the list? I would be a shame to waste machine time doing a double pass to eliminate chipping that could be resolved by ramping in outside the finished edge.

Rob,

I think the chip load charts are designed for max tool life but I imagine they do take finish edge into account as a secondary concern. More cut per inch may give a better edge but will shorten tool life at least that has been my experience with shaper & moulder cutters. I have been told that a faster feed rate will result in a better edge in some instances. I know with planers that is sometimes the case with woods that chip easily but seems counter intuitive with sheet stock. I am not discounting that it will work & am putting it on my list of things to try. Also as you say you add variables into the equation when you cut dissimilar materials or thicknesses.

Neville,
You said "Tooling is a black art" Amen brother!!

Kerry,

Do you mean vacuum hold down? If so I don't know how it is a variable unless the board is not held firmly enough to prevent it from moving??

I think that the new Vortex bit gives me the best edge of all the cutters I have used & I will fool with feed rates & spindle speed in an attempt to improve the edge but a board with a softer core is probably in my future. The Z core is formaldehyde free so maybe I'll have a smooth edge & be greener to boot.

Thanks
Gerry
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Re: Poor edge quality

Post by Kerry Fullington »

Gerry,

I just brought up the vacuum hold down because we were talking about going three flute and needing to increase the feed rate to get the correct chip load. You can (especially with plywood) get to a point where you can't increase feed because you can't hold the parts down, so it becomes part of the equation. Probably not as much of a problem with melamine.
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Re: Poor edge quality

Post by Gerry A Brown »

Thanks Kerry.
That makes sense I had not considered that.

Gerry
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Re: Poor edge quality

Post by Neville Bastian »

Those three flute are a bit dangerous in as much they get rid of the dust Ok if your using mdf or similar but if a operator uses it on particleboard by mistake it gets clogged up really quickly, then stops cutting, then starts burning then chucks the head out of alignment. How do I know? Don't ask. :(
Its a shame you cant have a barcode or those new codes you have in magazines that you attach to the chuck and the controller reads what tool the chuck has in it. Thats one area we sometimes get caught. Someone manually changes what should be in a tool holder without telling the controller. Or the other good one is manually puts in a chuck in the spindle and still have a chuck in the parking area. Man that causes some excitement and puts a smile on my Lietz salesmans face. :wall:
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Neville
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Re: Poor edge quality

Post by jason galbraith »

We use the same triple flute cutters on all our chipboard and MDF without problems Nev. We just slow the cutter down to about 60% feed speed when cutting MDF. Never really had a problem except occasionally our operator will cut down some random MDF packing sheets, that must have been tests for new glue or something and they just don't cut right at all.
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Re: Poor edge quality

Post by Neville Bastian »

Hi Jason,
Ha you have faith in your operator to know when to drop the speeds. Be careful on that dropping the feed speed as you may be getting less life out of the three flute than a two flute doing the same job. As you know the two flute is cheaper.
I am not a big fan in taking that risk that my operator will get it right. The cnc work is so mundane its easy to slip into another world. A world that I knew many years ago when I was younger. :lol:
Hope you are enjoying the warmer weather in your neck of the woods.
Regards

Neville
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Neville Bastian
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Re: Poor edge quality

Post by Neville Bastian »

Hopefully this may save someone some time if you are having edge quality issues. This is mainly evident on the X axis.
https://picasaweb.google.com/lh/sredir? ... feat=email

Regards

Neville
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Re: Poor edge quality

Post by Bryan Sullivan »

Thanks for the pics Neville! It looks like an easy thing to miss. Just want to reinvigorate the double pass conversation. Does anyone cut drawer parts and cabinet parts at the same time? How do you resolve the lip?
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Re: Poor edge quality

Post by Gerry A Brown »

On the pre-ramp plunge & ramp in it seems this always happens on the front edge, can anyone confirm this? Maybe it just seems that way.
If you could do the pre-ramp plunge outside the finished edge then ramp in & down that would be ideal. Has this ever been discussed?

Neville,

Thanks for the photos. I will check my machine to see if this is a problem. It's one of those things you don't think to check & as you say can waste a lot of time sorting it out.

Bryan,

We do mostly Tandembox metal drawers but once in a while cut .625" melamine for drawers. I have not found a solution for the lip or the poor edge other than sanding & that is a waste of time.

Gerry
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Re: Poor edge quality

Post by Josh Rayburn »

Gerry, I'd love to see that pre-ramp / ramp happen off the part edge (lead in). I suspect that it would increase the distance between parts, which is currently only about .025" now. Not sure if that would have a negative effect on yields for a lot of people, but the bottom line is if you have to cut an extra sheet it's still better than sanding every one of the parts that got cut now.
jnr
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Re: Poor edge quality

Post by Forrest Chapman »

Gerry, I wonder if you have your pre-ramp set to plunge into the board first then ramp. I set mine at .25" and it keeps the entry chip to a minimum. If you are running an un-mortised bit you will see a noticeable difference.

I have the ramp outside feature in CV and can tell you it is not an end all. You will need a little more space between the parts and there are some times when it will nip an adjacent edge but not many. It moves to a plunge depth outside the edge then ramps down and into the edge. I think the best feature for holding, cut quality, and speed is the continuous cut where it ramps in once and goes around all the parts before retracting.

Forrest
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