OK with the help of @cmartinez and a few others, I was successfully able to CAD my drawing. Now it is time for the CAM part and I am a bit confused by some definitions.


There are few settings I need some confirmation on

Depth Increment Depth increment of each machining pass. Determines the number of passes to reach the final target depth.

Final Depth Increment The depth increment of the final machining pass.

Target Depth The Z coordinate of the final machining depth.


First and second one seem easy. So if I make my target depth 1.5mm and my depth increment .1 it will make 15 passes?

What is the purpose of Final Depth Increment? Does that allow me to make my final pass different from the other passes? Why would I want to do this?

 

OK with the help of @cmartinez and a few others, I was successfully able to CAD my drawing. Now it is time for the CAM part and I am a bit confused by some definitions.


There are few settings I need some confirmation on

Depth Increment Depth increment of each machining pass. Determines the number of passes to reach the final target depth.

Final Depth Increment The depth increment of the final machining pass.

Target Depth The Z coordinate of the final machining depth.


First and second one seem easy. So if I make my target depth 1.5mm and my depth increment .1 it will make 15 passes?

What is the purpose of Final Depth Increment? Does that allow me to make my final pass different from the other passes? Why would I want to do this?

I'm not sure I understand either... but from what I gather, the Target Depth is the final, absolute depth of cut/machining that will be attained. The final depth increment would be the amount of material that would be removed on the tool's last pass.

 

Rough passes for greatest material removal don't typically leave a good final finish. Your CAM program will resolve "backward" from your finish pass depth. Surface speed (and/or tool speed) on your final pass can be varied too to achieve a good finish.

 

Rough passes for greatest material removal don't typically leave a good final finish. Your CAM program will resolve "backward" from your finish pass depth. Surface speed (and/or tool speed) on your final pass can be varied too to achieve a good finish.

So do I make the final pass deeper or more shallow than the others? And why?

 

Shallower. You are certainly familiar with the expression "blue chip". The surface speed is determined by the metal, alloy, tool, coolant and finish. The best removal rate will acquire a chip with a slight coloration change, and that is achieved by the depth of cut at correct surface speed. Your final pass must be deep enough to acquire a "clean chip" but not enough to get much coloration. How is this determined? My generation did it by careful adjustment during the cutting. I'm no toolmaker or small batch machinist, but was taught a bit by a couple great ones. I'm sure there's a good forum somewhere out there for just this sort of thing. I believe the charts in Machinery's Handbook may show a figure or multiplier and range.

 

I agree with tranzz... the last cut has to be just deep enough to remove the markings done by the previous one, plus a little more material. In theory, you have to readjust rpms and feed speed to obtain optimal results, but in practice that is seldom done.

 

I am cutting MDF on a cheap Chinese router / engraver.

Any recommendations on settings?

And another question. Mainly what I have on hand is engraving bits used for PCBs. I do have a few endmills. One about 2mm width. And I have a ball end mill maybe 1.5mm

Should I invest in some endmills? If so what size?


This is what I will be milling.

 

I am cutting MDF on a cheap Chinese router / engraver.

Any recommendations on settings?

And another question. Mainly what I have on hand is engraving bits used for PCBs. I do have a few endmills. One about 2mm width. And I have a ball end mill maybe 1.5mm

Should I invest in some endmills? If so what size?


This is what I will be milling.
View attachment 144700

For a piece like the one you're working on here, a two-flute 1/8" end mill oughta be enough... But I suggest you also buy 3/32" and 1/16" end mills, in case you need them later. Be careful who you buy them from. Always buy carbide (never HSS) and look around for a good price, you'll be surprised to see by how much it can vary.

 

For a piece like the one you're working on here, a two-flute 1/8" end mill oughta be enough... But I suggest you also buy 3/32" and 1/16" end mills, in case you need them later. Be careful who you buy them from. Always buy carbide (never HSS) and look around for a good price, you'll be surprised to see by how much it can vary.

Any idea on where to get a good price? what is a good price?

I found these

https://www.ebay.com/itm/10Pcs-Doub...090343&hash=item4675550b47:g:EfsAAOSwYDZaVxMM


Is tungstan the same as hss?

 

Or?

https://www.ebay.com/itm/Lukcase-1-...199435?hash=item3d50a81b8b:g:L2YAAOSwsBtaGySw

 

Any idea on where to get a good price? what is a good price?

I found these

https://www.ebay.com/itm/10Pcs-Doub...090343&hash=item4675550b47:g:EfsAAOSwYDZaVxMM


Is tungstan the same as hss?

No! ... tungsten carbide is far superior to hss (high-speed steel) ... even amazon has good prices on this sort of thing

 

Or?

https://www.ebay.com/itm/Lukcase-1-...199435?hash=item3d50a81b8b:g:L2YAAOSwsBtaGySw

Those look nice enough, but they have a round tip, which is good if you want to carve 3d surfaces, for instance.
For what you want here, a flat tip is more adequate.

 

What about these?

https://www.ebay.com/itm/141863252431

I understand 2 flute is better for chip ejection but won't I have just dust with MDF or plastic?

 

For a piece like the one you're working on here, a two-flute 1/8" end mill oughta be enough... But I suggest you also buy 3/32" and 1/16" end mills, in case you need them later. Be careful who you buy them from. Always buy carbide (never HSS) and look around for a good price, you'll be surprised to see by how much it can vary.

What is wrong with HSS?

 

What is wrong with HSS?

HSS is crap compared to tungsten. It's not as rigid, and therefore leaves a much rougher finish. Plus it loses its sharpness very quickly.

 

HSS is crap compared to tungsten. It's not as rigid, and therefore leaves a much rougher finish. Plus it loses its sharpness very quickly.

So what do you think about the 4 flute that I posted above vs 2 flute?

 

And what about a single flute spiral? What does that get you?

https://www.ebay.com/itm/152780406333

 

What about these?

https://www.ebay.com/itm/141863252431

I understand 2 flute is better for chip ejection but won't I have just dust with MDF or plastic?

So what do you think about the 4 flute that I posted above vs 2 flute?

For MDF, 2 flute is best. But you can perfectly work with 4 flute too, with a slower cutting speed. Otherwise the dust won't be ejected as efficiently and the finish might suffer a bit.

Those bits look good, and at a decent price too. It's worth buying a few and test them... The thing here is, that I suggest you buy at least one high-quality one with similar characteristics so that you may compare their performance. Only experience will tell you which bits are best for each particular purpose.

 

And what about a single flute spiral? What does that get you?

https://www.ebay.com/itm/152780406333

Take a closer look, those are high helix angle two flute straight end-mills, my friend. That sort of bit is pretty good for cutting non-ferrous materials.

 

For MDF, 2 flute is best. But you can perfectly work with 4 flute too, with a slower cutting speed. Otherwise the dust won't be ejected as efficiently and the finish might suffer a bit.

Those bits look good, and at a decent price too. It's worth buying a few and test them... The thing here is, that I suggest you buy at least one high-quality one with similar characteristics so that you may compare their performance. Only experience will tell you which bits are best for each particular purpose.

Well Pretty much my only option is slow with my cheap machine.


But I am guessing you mean the feed rate which I can get going pretty fast. My spindle speed is that one that is slow.