topic Re: Fusion posting random really slow speeds and feeds in Fusion Manufacture Forum

Fusion posting random really slow speeds and feeds

amxen — Sun, 23 Sep 2018 19:00:35 GMT

fusion is really testing my patience iv been trying all sorts to get it to post speeds and feeds code that aren't all over the place. Im trying to get my 4th axis set up. Iv made a small test model cutting a small pocket but every time it posts it will put some random really slow speed in there like F290. on the last test. Why is it doing this? So the 4th runs really really slow. I thought it was the post processor but iv tried other PP and it still put random slow moves in. could any one throw some light on it for me ? See lines 83 and 94 of the gcode

Re: Fusion posting random really slow speeds and feeds

amxen — Sun, 23 Sep 2018 20:05:35 GMT

This seems to be a problem when fusion is wrapping the tool path . Come someone check this for me Before i have to dump fusion and move on

Re: Fusion posting random really slow speeds and feeds

mike.mattera — Mon, 24 Sep 2018 21:56:15 GMT

It probably has something to do with how your machine is set to run rotary feeds. It can be Feed in Inches/Min or it can be set to Degrees/Min or Inverse time (the amount of time it takes to traverse this distance). What post and machine are you using? Probably need a Post guy to chime in on the options.

Re: Fusion posting random really slow speeds and feeds

mike.mattera — Mon, 24 Sep 2018 21:57:28 GMT

There's a Haas post that outputs Inverse time.

Re: Fusion posting random really slow speeds and feeds

daniel_lyall — Tue, 25 Sep 2018 05:51:14 GMT

@mike.mattera He is using Mach3 we when through mach3 and got it down to the post, It is putting out slow speeds when it is cutting.

Re: Fusion posting random really slow speeds and feeds

amxen — Tue, 25 Sep 2018 07:03:08 GMT

Hi back again . I have found a workaround using an older (possibly) modified postProcessor. The one Im using only posts one Feeds code at the start of the code. The one that is inside fusion posts a new Feed on every line of gcode. on random lines it sets a speed of F291 or F345, all the other Feeds are like F2000+ Eliminating the changing feed has fixed the problem but. The PP im using now only Posts one Feed at the start of F750 or what ever i set it to in fusion. I'm not sure this is how it should work but it works .

Re: Fusion posting random really slow speeds and feeds

amxen — Tue, 25 Sep 2018 07:10:02 GMT

@daniel_lyall haha didnt recognise the name

Re: Fusion posting random really slow speeds and feeds

daniel_lyall — Tue, 25 Sep 2018 07:14:11 GMT

No I still can not find the problem. The newest Mach3 post I tried it an hour ago it was fine it was putting the A axis speed out correctly on all 3 wrap toolpaths this was on an Apple, I am trying windows again now.

Re: Fusion posting random really slow speeds and feeds

amxen — Tue, 25 Sep 2018 09:00:38 GMT

I know IV got it running but it would be nice to find out why the pp that's in fusion is output the random feeds

Re: Fusion posting random really slow speeds and feeds

daniel_lyall — Tue, 25 Sep 2018 09:17:48 GMT

There is a speed difference in the A axis moves but it is correct in the new post, I have never seen a difference like what you were seeing.

It could be a random glitch that stuck for some time in cam or cad or the post, if it can get nailed down to a workflow it would get fixed.

Re: Fusion posting random really slow speeds and feeds

narzinskin — Tue, 25 Sep 2018 13:20:21 GMT

Sounds like it is posting inverse time.

Re: Fusion posting random really slow speeds and feeds

amxen — Tue, 25 Sep 2018 13:23:13 GMT

Could you explain this for me ?

Re: Fusion posting random really slow speeds and feeds

narzinskin — Tue, 25 Sep 2018 13:48:00 GMT

the short version is Feed (F) is posted as the time it takes to for the axis to make the move and there must be a feed on every line. G93 turns it on and G94 off. the time on most controls is milliseconds i believe.

Re: Fusion posting random really slow speeds and feeds

amxen — Tue, 25 Sep 2018 15:56:42 GMT

Why is it posting most lines in the F2000 to F5000 mark and then a random line of f291 this line would be incredibly slow. This is not the machine it's from fusion through the pp . That would be logic

Re: Fusion posting random really slow speeds and feeds

bob.schultz — Wed, 26 Sep 2018 17:27:15 GMT

@amxen wrote:

fusion is really testing my patience iv been trying all sorts to get it to post speeds and feeds code that aren't all over the place. Im trying to get my 4th axis set up. Iv made a small test model cutting a small pocket but every time it posts it will put some random really slow speed in there like F290. on the last test. Why is it doing this? So the 4th runs really really slow. I thought it was the post processor but iv tried other PP and it still put random slow moves in. could any one throw some light on it for me ? See lines 83 and 94 of the gcode

The Mach3 post processor is outputting feed rates for rotary moves using Inverse Time (G93) feed rates, which is why you see feed rates on every block as required by the control. Per the manual, the Mach3 should accept Inverse Time feed rates, and obviously accepts the G93 code or you would get an error.

To calculate the machining time the post processor calculates the tool tip movement based on the radius of the part and the XYZ movements on the machine. For the calculations below, I will keep it simple and just explain the tool tip movement based on the part radius.

Block: A-4.186 F360.0353

Part radius = 6.5 (based on the Z-axis position).

Part circumference = 2 * PI * Radius = 40.8 mm

Angular move = -4.186 - 20.296 = 24.482 degs

Tool Tip Movement = (24.482 / 360) * 40.8 = 2.775 mm

Move Time = 2.775 / 1000 = .002775 mins or .12 secs

Feed Rate Number = 1 / .002775 = 360.360 (close to the output F-value)

Block: X-11.249 A20.295 F291.6342

Part radius = 6.5 (based on the Z-axis position).

Part circumference = 2 * PI * Radius = 40.8 mm

Angular move = 20.295 - (-9.919) = 30.214 degs

Tool Tip Movement = (30.214 / 360) * 40.8 = 4.029 mm

Move Time = 4.029 / 1000 = .004029 mins or .24 secs

Feed Rate Number = 1 / .004029 = 248.201 (round-off due to X-movement, but still close to the output F-value)

As you can see the calculations are correct. If these moves take longer on the machine than the calculated times, then there is probably a problem with the control software in processing inverse time feed rates.

Specifying a fixed FPM feed rate should not be correct, since the control does not typically know the part radius and cannot calculate the correct machining time. You can change the feed rate calculation to use DPM feed rates instead of Inverse Time by changing the following variable in the post.

var useInverseTimeFeed = false; // use DPM feeds (change to false)

You will still see multiple different feed rate numbers output, but they will be more consistent from block to block.

Re: Fusion posting random really slow speeds and feeds

amxen — Wed, 26 Sep 2018 18:03:27 GMT

Thanks very much for this response. iv changed it to false and the Feed look a lot better. Iv not tried running the code but there are no random low Feeds that has been slowing my machine down. So im very hopeful