Trochoidal Pocket & Profile MOPs plugin (HSM)

[kvom]

I used the trocho profile once when I needed to mill some 3/4" aluminum plate.  I don't have coolant on my mill, so a deep 1/2" slot will weld chips pretty quickly.  By cutting the profile 3/4" wide using climb, my airblast has time to blow away chips when the tool moves free to start the next slice.

I'd use this MOP for most deep slots and any that are wider than the tool.

No shaking or banging with my mill (PP control).

[devmonkey]

I needed an HTD5 pulley for a project, this was a bit odd as it needed to be fixed to a spinning bearing housing rather than to a shaft so I decided to make one on the machine. I used the cambam trochoidal plugin for the roughing allowing the entire part to be milled with a 3mm endmill, took a bit longer but meant no tool change. Part was cut dry with air to clear chips, worked out really well.

Trochoidal clearing is excellent, no gummy chips sticking to the endmill. This was cut from some 5000 series (not sure exact spec) scrap plate, it is quite gummy, would have been better in 6061 but I didn't have any to hand. Still the part is more than serviceable for its intended purpose which is to drive a multi-turn encoder (near zero load). Was cut at 3mm DOC, 15% stepover, 24k rpm, 3000mm/s for clearing (although the machine never gets anywhere near this on this part due to the tiny radius of the spirals).

I will probably recut it with a high speed profile to finish, the finish pass was way too slow (600mm/s) which led to rubbing and the surface finish not being perfect. This was entirely my fault for rushing the CAM and not setting the feed.

https://www.youtube.com/watch?v=skiw7pmDoQk

Thanks for the excellent plugin!

[Bubba]

Nice!

[Dragonfly]

I do some HTD pulleys for myself and before milling the teeth I drill the material down to the bottom with a suitable drill at the bottom of the pulley (minor diameter). This may lead to holes in the flange but it is not a problem. But help a lot milling and shaping the teeth with even a bit large tool as the narrowest part of the profile is already done by the drill.  I also usually mill a wide channel around the outer diameter (sometimes even remove the stock if the pulley part can be held down with a central screw. Thus only a small amount of material is left for milling the teeth with less tool load and achieving a good shape.
The most complicated part is to place the drill point at the exact place so the hole coincides with the bottom curve of tooth profile. Then the point is polar array copied around the center at the required step angle.

[dh42]

Hello

A way to easy drill the HTD pulley


the following plugin are used:

http://www.atelier-des-fougeres.fr/Cambam/Aide/Plugins/MarkCenterofArcs.html

http://www.atelier-des-fougeres.fr/Cambam/Aide/Plugins/invert_selection.html

++
David

[CKerv]

Could someone explain how to install this plug in?

[EddyCurrent]

Could someone explain how to install this plug in?

Read this; https://cambamcnc.com/forum/index.php?topic=5986.msg50892#msg50892

[Dragonfly]

I did a quick search and didn't find this discussed.
Often one uses copy/paste a MOP to get a new MOP with set parameters and only change the drawing objects.
This affects only 'Trochoidal pocket' MOP and only under Linux. When trying to paste there is an error message "Parameter name:field". And no pasting.
Under Windows pasting is normal. So I guess it's not a general bug for CB but something specific to its Linux version and its work with the clipboard.

P.S. It came to me that this is a plugin, not an internal CB MOP. Which perhaps makes tracking the reason more complicated.

[EddyCurrent]

The plugin was written by JK who understands well the mechanics of copy & paste, unfortunately he does not visit this forum as often as he used to.

See here; https://cambamcnc.com/forum/index.php?topic=7564.msg60787#msg60787
and here; https://cambamcnc.com/forum/index.php?topic=7531.msg60615#msg60615

Maybe there are clues regarding the Linux version in there ?

[dh42]

Hello

Topic merged with the main subject
(this is not a CamBam bug)

++
David

[Dragonfly]

Opening the .cb file in a text editor and replicating the MOP there giving it a new name acts as a workaround.
One thing I noticed is the way the MOP is declared in comparison to the other native MOPs.

Code: [Select]

        <mop xsi:type="MOPTrochopock" Enabled="true">
          <StepOver state="Value">0.12</StepOver>
          <DepthIncrement state="Value">3.5</DepthIncrement>
          <FinalDepthIncrement state="Default">0</FinalDepthIncrement>
          <MillingDirection state="Default">Climb</MillingDirection>
          <CutOrdering state="Default">DepthFirst</CutOrdering>
          <TargetDepth state="Value">-7</TargetDepth>
          <LeadInMove state="Value">
            <LeadInType>Spiral</LeadInType>
            <SpiralAngle>2</SpiralAngle>
            <TangentRadius>0</TangentRadius>
            <LeadInFeedrate>0</LeadInFeedrate>
          </LeadInMove>
 
While a standard pocket is declared in this way:

Code: [Select]

        <pocket Enabled="true">
          <TargetDepth state="Value">-7.5</TargetDepth>
          <DepthIncrement state="Default">0.5</DepthIncrement>
          <FinalDepthIncrement state="Default">0</FinalDepthIncrement>
          <CutOrdering state="Default">DepthFirst</CutOrdering>
          <StepOver state="Default">0.4</StepOver>
          <StepoverFeedrate state="Default">Cut Feedrate</StepoverFeedrate>
          <MillingDirection state="Default">Climb</MillingDirection>
 

[EddyCurrent]

I believe I have finally managed to get version 2.4.0 built for CamBam V1.0 64bit
Please find the plugin attached .

[Bubba]

Thanks Eddy.

[dave benson]

Thanks Eddy, I thought this might be difficult to do without the extra libs.

[qwerty]

Hi, is the following a bug or a feature?

There is a 30 x 30 mm square in attached .cb file and a standard Pocket MOP and a TrochoPocket MOP. Both MOPs with the same settings, tool diameter set to 10 mm, Stepover set to to 0.1 (for easy math). While the Pocket MOP cuts exactly 10 mm * 0.1 = 1 mm of a stock in each step, the TrochoPocket MOP cuts 0.68 mm instead of expected 1 mm. Why?

Now try resize the square to 100 x 100 mm and regenerate toolpaths. Pocket MOP as expected, still 1 mm actual stepover. The TrochoPocket MOP actual stepover is increased compared to previous 0.68 mm. Why?

The same observation for TrochoProfile MOP. Try TrochoProfile MOP on a straight line, tool diameter 10 mm, stepover 0.1. Do you get 1 mm actual stepover measured on generated toolpath?

Trying to understand this behavior / inconsistency.

Thanks.