Frage Plunge and feed rates

Have broken 2 end mills

What is plunge ? i tryed to translate to my language but didnt work

What feed rates and cut passes is normal for
Balsa
Plywood
MDF

Regards Jörgen

It happens, don't worry!

Plunging (how I understand it) is when your z-axis first penetrates the material you're cutting instead of going in at 90 degrees just like a drill, it pushes the tool in and down/Y- (or up Y+) at the same time so that it doesn't blunt the tool you're using. THis is most beneficial when you are engraving or using a specialist tool peice that you don't want to blunt.

I don't think its really relavent for standard milling in wood or plastic, but someone with more experience may be able to correct me here?


For plywood, I use 18k RPM - 2mm passes - 5mm/second feed - 2mm/second plunge this seems to work well for me, but always make sure that you start slow and build up, different grade of Plywood are stronger/weaker.

Alex

plunge is the speed in the Z direction.

feed rate is the speed in the X and Y directions.

if you plunge too deep you will break tools. Also you need to make sure your spindle speed is high. For first tests - put proxxon up to max - only plunge 0.25-0.5mm deep and build up slowly - get confidence and see how the machine works sounds. always start very shallow depths then build up confidence.

take your time.

I am very happy for both answers and also fast answers !

I hope someone else also can use this info, its gold for a newbie

/Jörgen

post your results - hopefully not broken bits!

Tryed Balsa and plywood and worked perfect !!!

Maybe we can make some table for diffrent materials and mills

would be easy for us and also for more beginners like me

Thanx

Ah what was I think of then, when you plunge in at an angle?

Havent come so far so i made 3d !
Only RC details
if i understand you correctly

When milling - its best to ramp plunge. So you don't go straight down in Z. For example when milling Aluminium on larger machines its best to ramp / helical plunge. This puts less pressure on cutter. Milling cutters cannot remove material in the drilling direction as well as drill bits.

There is a ramp plung option in the toolpath section of Vcarve.

Hi,
I just did my first test carving letters into plywood, the Plunge rate Z down is nice and slow but also for Z up.
is wouldn't happen to be a way to tell it to go up at a different speed? since going up its not doing any cutting. I had my safe height set higher then I needed and it took a lot of time between letters.

if your Z axis movements are slowing you down - then drop the rapid clearance height. the machine will move back to the rapid clearance gap each time it finished an operation.

are you using Cut2D?

If this rapid clearance height is high it can waste time..

However - careful careful careful as this setting will save itself... we did this for a PCB operation and had the Z clearance at 0.5mm... then changed to aluminium job next day and the 0.5 remained... the larger router crashed a 6mm carbide tool straight into the clamps and the tool was f***ed... 30£'s worth of tool gone... so be careful.

its always safer to keep the Z clearance high as it reduces crash risk

NOTE: there is a machine home position also - this is 20mm by default (I think) so the machine will always go up to +20mm. if you ave a high workpiece this can stop the machine retracting to the Z limit switch.



when the machine is moving between jobs it will use the g00 command - this is the rapid movement command - this will be the max movement speed of the machine. in the case of STEPCRAFT 1 will be 1800mm/min. STEPCRAFT 2 3,000mm/min

I am new at CNC, only experience I have is with vinyl cutter and vectors. I did not buy Vcut or MACH3, I want to see if software I have can do what I need. I am finding out there is issues trying to export vector to a DXF (or it was CorelDraw's export), and some g-code generators works with DXF only and others with SVG. So I wanted to start with the most basic engraving as a first test and found EASEL.com, its web base and can download the g-code (click Machine>advanced) it gave me option for Safety Height and Step Over, I do not know what step over% is. I have much to learn and have other software to try.

here is video of our first run,


do you think X/Y was too fast?

Z Homing height is fully up, I configured the safety height in the program that creates the g-code, but have not seen anything called rapid clearance.
Looking at the codes,

• G1 Z5.080 F228.6
• G0 X37.325 Y33.926
• G1 Z-1.270 F228.6

it looks like it is using G1 for raising the Z and G0 to move to next job.
cool!, as I'm writing this post its making sense to me, I need to read up on Gcodes and Mcodes. And better software to create the G-codes for more control.

one thing the vinyl cutter has I wished this has is 'show me' , what it does is with cutter up, it does a boundary run showing you how far the cutting will go so you can make sure it does not go off your material. is there such thing in UCCNC?

Thank you

G01 is machining instruction

G00 is movement between cutting.

looks good - well done!!


One general comment on your video - your cutter is really long with large stick out. This will result in amplification of vibrations. What you want is to have cutter stickout just larger than your cutting depth. This gives the best results.

The closer you can get the bottom of the cutter to the collet the less vibration will come from the cutter - but this brings the machine down closer to clamps etc.

Just some of my parameters to compare:

For plywood I use usually 420-480 mm/s (7-8mm/s), for harder wood 360 (6mm/s) feed rate.
I use usually 120mm/s (2mm/s) plunge rate.

With 1mm I go @20kRPM and I cust up to 4mm with no problem, also with 0,8mm.

With 3+mm I go only 2mm max.

My Z-clearance is mostly 2-3 mm, had never anything breaking because of that unless I left something on the table and the tool crasked into it.

The main reason why I break tools is that I made a mistake, and there were many of them so far. But since 2 month tools get older and replaced mainly when they are not sharp anymore

I cut (profile) Birch plywood with a 3mm bit at 900mm/min, 300mm/min plunge rate, 2mm pass depth - no problems, hundreds of items cut. This is with Stepcraft HF350 at 20000rpm, cutting plywood up to 9mm thick.

I v-carve text with a 6mm v-bit using the same feed/plunge rates (60degree and 90degree v-bits). Same rates are good with 2mm 60degree v-bit.

When I was using plywood from China, these feed rates broke several bits.

If I know a toolpath is not going deep (less than 1mm) I will happily run up to 1200mm/min in plywood.