[madaouk]

I was cutting cheets of brass in 2D designs using Feed rate: 400 mm per minit ..... but when the cutting tool I am using handle more speed in feed rate , up tp 1000 mm per minit , the designs was not cut properly , so does any one has solution for this ?

[philbur]

What size and type of cutter were you using and what spindle speed.

Phil

I was cutting cheets of brass in 2D designs using Feed rate: 400 mm per minit ..... but when the cutting tool I am using handle more speed in feed rate , up tp 1000 mm per minit , the designs was not cut properly , so does any one has solution for this ?

[impact]

The tormach to my knowledge is not a high speed machine, you must lower the feed to within machine acceleration and cutting rate limits.

[lentzie]

The rapid traverse speed for the Tormach is 65 IPM. I have experimented with cutting low tolerance parts at that speed with fairly good results. Runing faster than this resulted in missed steps.

Dave

[madaouk]

What size and type of cutter were you using and what spindle speed.

Phil

I am usine 0.8mm round carbide with spindle speed of 29000rpm ...

[madaouk]

The rapid traverse speed for the Tormach is 65 IPM. I have experimented with cutting low tolerance parts at that speed with fairly good results. Runing faster than this resulted in missed steps.

Dave

Dave

The speed you r talking about is in inc .. I am using metric calculations in mm , so 1000 mm per min is 40 Ipm , and the design I am cutting as closed curves are in the range of 0.5 cm or 0.2 inc . what do you mean by low tolerance parts ?

Mazen

[impact]

1000mm/min is 39.37 ipm which is fine in a straight line... but as soon as the machine has to go around corners the cutting speed overloads acc/dec limits of the stepper motors causing lost steps.

I work on both high speed matsuura RA-2G and standard RA-2F the high speed machining macros allow the ra-2g to rip around in aluminum at 500 IPM but the cutting speed of the RA-2F is limited to around 150 ipm... although rapid is 400 IPM. You are asking alot of the tomach for that sort of speed, it is only stepper driven.

[lentzie]

Madaouk,

I was cutting 3D wooden toy parts. The geometry allowed for mostly straight line cutting with very few curves in the X and Y axies. Z axis steps were missed at 65 IMP. When slowed down to approx 40 IPM the Z axis held it's position.

On that project a tolerance of +/_ .040 was acceptable.

I agree with Impact, you are asking more of the Tormach than it was designed for.

Dave

[madaouk]

1000mm/min is 39.37 ipm which is fine in a straight line... but as soon as the machine has to go around corners the cutting speed overloads acc/dec limits of the stepper motors causing lost steps.

I work on both high speed matsuura RA-2G and standard RA-2F the high speed machining macros allow the ra-2g to rip around in aluminum at 500 IPM but the cutting speed of the RA-2F is limited to around 150 ipm... although rapid is 400 IPM. You are asking alot of the tomach for that sort of speed, it is only stepper driven.

what about if we changed the stepper motor ?

[impact]

what about if we changed the stepper motor ?

The OEM steppers are plenty powerful, it is the limitation of the stepper driving system, they are inherently slower than servos.

Unfortunately I think you are hooped to a slower feed rate or bigger radii with the tormach.

[madaouk]

I am working with jewelry , so all my cuts will be small and micro , sory for asking you too much ... last question ... So is there machines with micro motor or specialy for mini cutting , or the servo morot is better than the stepper motor and it would do the job?

[philbur]

So are you using the proxxon high speed spindle. If so you may need a better spindle if you want to push it hard. Others may be able to give you detailed advice on this. In what way was the design not cut correctly, a photograph would be useful.

If this is the size work you normally do then the Tormach may not have been the best choice.

Phil

I am usine 0.8mm round carbide with spindle speed of 29000rpm ...

[madaouk]

[QUOTE=philbur;541159]So are you using the proxxon high speed spindle. If so you may need a better spindle if you want to push it hard. Others may be able to give you detailed advice on this. In what way was the design not cut correctly, a photograph would be useful.

If this is the size work you normally do then the Tormach may not have been the best choice.

Phil[/QUOTE
this is supposed to be an earing .... the lines between the cuts were equaly designed but in the 1000mm feed was not cut well , 400mm was perfect ..

[philbur]

Is the photo the 400mm or the 1000mm feedrate. A photo of the 1000mm is the one of interest. Also you did not answer as to what spindle you are using for 29,000 rpm.

Phil

PS: A photo of both would be good.

[quote=madaouk;541318]

So are you using the proxxon high speed spindle. If so you may need a better spindle if you want to push it hard. Others may be able to give you detailed advice on this. In what way was the design not cut correctly, a photograph would be useful.

If this is the size work you normally do then the Tormach may not have been the best choice.

Phil[/QUOTE
this is supposed to be an earing .... the lines between the cuts were equaly designed but in the 1000mm feed was not cut well , 400mm was perfect ..

[zephyr9900]

madaouk,

For determining machining speeds and feeds I trust Machinist Mate software. Assuming your 0.8mm cutter (0.032" in my familiar units) is carbide, MM reccomends 47746 rpm and 10.7ipm (272mm/min) based on chip loading. My machining of brass and nickel silver with a 0.5mm cutter, slowing the cutting speed in ratio to the 20000 maximum RPM of the Proxxon spindle, seems to bear out the suitability of the MM reccomendations (I haven't broken a cutter )

If you are already getting 400ipm it sounds to me that you are doing very well...

Best regards,

Randy

[madaouk]

[quote=philbur;541326]Is the photo the 400mm or the 1000mm feedrate. A photo of the 1000mm is the one of interest. Also you did not answer as to what spindle you are using for 29,000 rpm.

Phil

PS: A photo of both would be good.

I am using a router " kiper " as an extention on the machine , its chines and very cheap , but need to be changed evry 3 month .. but the spindle it not the problem the steper motor is not handeling the speed thats why I askd you : if the servo motor of the axis is better than the stepper motor ..
the other peice is not a was sent for acceptance after it was fixed by hand ..
Mazen

[zephyr9900]

1000mm/min is 39.37 ipm which is fine in a straight line... but as soon as the machine has to go around corners the cutting speed overloads acc/dec limits of the stepper motors causing lost steps.

Very true, impact. Lateral acceleration around a circular arc is v^2/r. If you halve the radius the acceleration doubles, and if you double the speed, the acceleration quadruples. I have seen sophisticated CNC software that automatically adjusts the cutting speed based on the upcoming G2 or G3 radius, but in our case we need to hold back for path stability.

Best regards,

Randy

[madaouk]

madaouk,

For determining machining speeds and feeds I trust Machinist Mate software. Assuming your 0.8mm cutter (0.032" in my familiar units) is carbide, MM reccomends 47746 rpm and 10.7ipm (272mm/min) based on chip loading. My machining of brass and nickel silver with a 0.5mm cutter, slowing the cutting speed in ratio to the 20000 maximum RPM of the Proxxon spindle, seems to bear out the suitability of the MM reccomendations (I haven't broken a cutter )

If you are already getting 400ipm it sounds to me that you are doing very well...

Best regards,

Randy

I got the 400 mm not IPM if you were refering to me , and the tool was strong enought to make up to 1000mm and I think it can do more ...
I am using the SURF software and its calculating for 0.8 mm round carbide tool ... the speed of spindle: 28000 rpm ..... and the feed rate up to: 9469 MMPM ....... but unfortunatly I am using 10% of that speed , so why is that defference between the two softwares .......
best regards
madaouk .. Mazen

[philbur]

MEpro comes up with very similar numbers.

madaouk,

For determining machining speeds and feeds I trust Machinist Mate software. Assuming your 0.8mm cutter (0.032" in my familiar units) is carbide, MM reccomends 47746 rpm and 10.7ipm (272mm/min) based on chip loading. My machining of brass and nickel silver with a 0.5mm cutter, slowing the cutting speed in ratio to the 20000 maximum RPM of the Proxxon spindle, seems to bear out the suitability of the MM reccomendations (I haven't broken a cutter )

If you are already getting 400ipm it sounds to me that you are doing very well...

Best regards,

Randy

[philbur]

It seems like you are doing well at 400mm/min with 29,000 rpm. At 1000 mm/min it's suprising that you are not breaking the cutter. The photo you posted shows issues that would normally be attributed to a cheap spindle.

I'm no expert but possibly if you used a larger motor with belt drive to keep the motor speed down and the torque up. Of course the down side would be a reduction in resolution.

Just a thought
Phil

PS: you still don't say if the photo is 400 or 1000 mm/min

[quote=madaouk;541341]

Is the photo the 400mm or the 1000mm feedrate. A photo of the 1000mm is the one of interest. Also you did not answer as to what spindle you are using for 29,000 rpm.

PS: A photo of both would be good.

I am using a router " kiper " as an extention on the machine , its chines and very cheap , but need to be changed evry 3 month .. but the spindle it not the problem the steper motor is not handeling the speed thats why I askd you : if the servo motor of the axis is better than the stepper motor ..
the other peice is not a was sent for acceptance after it was fixed by hand ..
Mazen