Messages

1

General Mach Discussion / Re: Help for a new user - circles are not circles and its not backlash....

« on: October 24, 2013, 07:02:38 AM »

Thanks Hood.

I accept what you say however the Y axis is a ball-screw and doesn't seem to have any backlash at all that I can find with the DTI? Also I found this info on the CamBan site which I am don't really understand and I have copied it below.  The circles are so far out that I would have thought they would have shown up on my backlash checks is that a fair comment? Any suggestions you have for testing/eliminating the Y axis problem would be appreciated as I cant see how (it being a ball screw) i can adjust it?

Info from CamBam

Crazy looking arcs (crop circles) or 'Radius to end of arc differes from radius to start' error when loading gcode into Mach3 or other CNC controller.

Gcode arcs specify a center point (I & J parameters), which can be absolute coordinates or relative to the first arc point. A problem will occur if CamBam and the controller are configured to use different arc center methods.

To change the arc center method in CamBam, select the Machining folder. Then change the ArcCenterMode property to Absolute or Incremental to match your controller configutation. Alternatively, change your controller software to match the CamBam setting.

For Mach3, it is sufficient to just select Mach3 in the Machining - PostProcessor property. Mach3 recognises non-standard gcodes G90.1 and G91.1 which are used to specify the arc center mode used in the gcode.

ArcCenterMode and PostProcessor properties are set per drawing. These can be set as the default for all new drawings by specifying a DrawingTemplate property in the system configuration settings.

2

General Mach Discussion / Re: Help for a new user - circles are not circles and its not backlash....

« on: October 24, 2013, 06:10:46 AM »

Sorry for the delay in responding (health issues) here is my code and also a picture of the results on a piece of aluminium. I hope someone can help. I have yet to try some of the suggestions above so the answer may already be there, but just in case.........

Code using CamBam

<?xml version="1.0" encoding="utf-8"?>
<CADFile xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" Version="0.9.8.0" Name="two circles for trial">
  <layers>
    <layer name="Default" color="127,255,0">
      <ModificationCount>0</ModificationCount>
      <objects>
        <circle id="1" c="22,0,0" d="25">
          <ModificationCount>3</ModificationCount>
          <mat m="Identity" />
        </circle>
        <circle id="2" c="-31,0,0" d="50">
          <ModificationCount>3</ModificationCount>
          <mat m="Identity" />
        </circle>
      </objects>
    </layer>
  </layers>
  <MachiningOptions>
    <Stock>
      <PMin>0,0</PMin>
      <PMax>0,0</PMax>
      <Color>255,165,0</Color>
    </Stock>
    <ToolProfile>Unspecified</ToolProfile>
  </MachiningOptions>
  <parts>
    <part Name="Part1">
      <machineops>
        <profile>
          <WorkPlane state="Default">XY</WorkPlane>
          <OptimisationMode state="Default">Experimental</OptimisationMode>
          <RoughingFinishing state="Default">Roughing</RoughingFinishing>
          <ToolDiameter state="Default">6</ToolDiameter>
          <ToolNumber state="Value">6</ToolNumber>
          <ToolProfile state="Default">EndMill</ToolProfile>
          <PlungeFeedrate state="Default">300</PlungeFeedrate>
          <CutFeedrate state="Value">300</CutFeedrate>
          <MaxCrossoverDistance state="Default">0.7</MaxCrossoverDistance>
          <StartPoint state="Default">0,0,0</StartPoint>
          <CustomMOPHeader state="Default" />
          <CustomMOPFooter state="Default" />
          <Name>50mm</Name>
          <StockSurface state="Default">0</StockSurface>
          <RoughingClearance state="Default">0</RoughingClearance>
          <ClearancePlane state="Default">3</ClearancePlane>
          <SpindleDirection state="Default">CW</SpindleDirection>
          <SpindleSpeed state="Default">1000</SpindleSpeed>
          <SpindleRange state="Default">0</SpindleRange>
          <VelocityMode state="Default">Undefined</VelocityMode>
          <primitive>
            <prim>2</prim>
          </primitive>
          <TargetDepth state="Value">-2</TargetDepth>
          <DepthIncrement state="Default">0.4</DepthIncrement>
          <FinalDepthIncrement state="Default">0</FinalDepthIncrement>
          <CutOrdering state="Default">DepthFirst</CutOrdering>
          <CutWidth state="Value">3</CutWidth>
          <StepOver state="Default">0.4</StepOver>
          <StepoverFeedrate state="Default">Plunge Feedrate</StepoverFeedrate>
          <InsideOutside state="Default">Outside</InsideOutside>
          <MillingDirection state="Default">Conventional</MillingDirection>
          <CollisionDetection state="Default">True</CollisionDetection>
          <CornerOvercut state="Default">False</CornerOvercut>
          <LeadInMove state="Default" />
          <LeadOutMove state="Default" />
          <HoldingTabs state="Default">
            <TabMethod>None</TabMethod>
            <Width>3</Width>
            <Height>3</Height>
            <MinimumTabs>3</MinimumTabs>
            <MaximumTabs>6</MaximumTabs>
            <TabDistance>40</TabDistance>
            <SizeThreshold>4</SizeThreshold>
            <UseLeadIns>False</UseLeadIns>
            <TabStyle>Triangle</TabStyle>
          </HoldingTabs>
          <SideProfile state="Default" />
        </profile>
        <pocket>
          <WorkPlane state="Default">XY</WorkPlane>
          <OptimisationMode state="Default">Experimental</OptimisationMode>
          <RoughingFinishing state="Default">Roughing</RoughingFinishing>
          <ToolDiameter state="Default">6</ToolDiameter>
          <ToolNumber state="Value">6</ToolNumber>
          <ToolProfile state="Default">EndMill</ToolProfile>
          <PlungeFeedrate state="Default">300</PlungeFeedrate>
          <CutFeedrate state="Value">300</CutFeedrate>
          <MaxCrossoverDistance state="Default">0.7</MaxCrossoverDistance>
          <StartPoint state="Default">0,0,0</StartPoint>
          <CustomMOPHeader state="Default" />
          <CustomMOPFooter state="Value" />
          <Name>25mm</Name>
          <StockSurface state="Default">0</StockSurface>
          <RoughingClearance state="Default">0</RoughingClearance>
          <ClearancePlane state="Default">3</ClearancePlane>
          <SpindleDirection state="Default">CW</SpindleDirection>
          <SpindleSpeed state="Default">1000</SpindleSpeed>
          <SpindleRange state="Default">0</SpindleRange>
          <VelocityMode state="Default">Undefined</VelocityMode>
          <primitive>
            <prim>1</prim>
          </primitive>
          <TargetDepth state="Value">-3</TargetDepth>
          <DepthIncrement state="Default">0.4</DepthIncrement>
          <FinalDepthIncrement state="Default">0</FinalDepthIncrement>
          <CutOrdering state="Default">DepthFirst</CutOrdering>
          <StepOver state="Default">0.4</StepOver>
          <StepoverFeedrate state="Default">Plunge Feedrate</StepoverFeedrate>
          <MillingDirection state="Default">Conventional</MillingDirection>
          <CollisionDetection state="Default">True</CollisionDetection>
          <LeadInMove state="Default" />
          <LeadOutMove state="Default" />
          <RegionFillStyle state="Default">InsideOutsideOffsets</RegionFillStyle>
          <FinishStepover state="Default">0</FinishStepover>
          <FinishStepoverAtTargetDepth state="Default">False</FinishStepoverAtTargetDepth>
        </pocket>
      </machineops>
      <Stock>
        <PMin>0,0</PMin>
        <PMax>0,0</PMax>
        <Color>255,165,0</Color>
      </Stock>
      <ToolProfile>Unspecified</ToolProfile>
      <Nesting>
        <BasePoint>0,0</BasePoint>
        <NestMethod>None</NestMethod>
      </Nesting>
    </part>
  </parts>
  <ActiveLayer>Default</ActiveLayer>
  <ActivePart>Part1</ActivePart>
</CADFile>

picture of results (I have yet to repair the y axis bracket although I think it may have been there before?)

3

Mach4 General Discussion / Re: New people welcome !! Come in here and introduce your self!

« on: October 16, 2013, 04:57:19 PM »

Hello Graham,

Nice to hear from you, perhaps you can email off forum?  I think my email is available, if not I will let you have it in whatever way I can.

Kind regards, Mike

4

General Mach Discussion / Re: Help for a new user - circles are not circles and its not backlash....

« on: October 16, 2013, 04:53:53 PM »

Thanks Jeff I will try what you say when next in the shop

5

General Mach Discussion / Re: Help for a new user - circles are not circles and its not backlash....

« on: October 15, 2013, 06:52:38 AM »

Hello Vogavt,
 
Thanks for the reply, One question further before I go any  further, would a loose motor mount on the Y axis cause this oval circle?
I only ask because I have just tried to do a circle in MDF (less stress on the 3 axis) and still get the oval phenomenon? I am just having to go out and have no time, sorry.  I just spotted the bottom part on the mount has come apart leaving some movement?

Will look in later and give a better reply. I will have to weld now the bottom so in a sense I will answer myself but this may be a few days off.......If it can I will at least have a chance to rest my brain. I am failry convinced there is no backlash but have been wrong before.

Mike

6

General Mach Discussion / Help for a new user - circles are not circles and its not backlash....

« on: October 14, 2013, 09:51:46 AM »

Hello, If I have posted this help request in the wrong place then I apologise, I am new to the forum. I have introduced myself though in the newcomers section.

I have a converted round column RF25 milling machine in the UK by Axminster tools. I have fitted new ball-screws to the X and Y axis (so eliminating backlash) and calibrated the three axis by DTI, cutting a part and checking measurements. I have adjusted the gibs for both X and Y again using DTI. I have checked the Z axis for slackness with the DTI.
 I have also tuned the motors to run the best I can and the conversion works very well.....as long as it doesn't include a circle. I have checked again both table security by dti and spindle movement.

Therefore I think it may be a setting problem, as when watching the Y axis motor, at the point the straight lines occur (along the X axis top and bottom) it slows down and whilst never stopping, slowly reverses before speeding up to produce a normal circle is produced again, until it is in the opposite position, where it again slows down before changing direction. At the same time the X axis keeps to the same speed for all the run.

I did find one suggestion where they said the acceleration for both X and Y should be the same. This seemed logical to me, as it was slowing down then speeding up again, so I made those changes. To find the problem still exists.  I did save the axis settings and did this procedure several times. It seems to me that both motors are working fine until the Y axis motor starts its slowing down etc.  I have also replaced the motor with one I have spare ready to make a 4th axis.......

Checking the internet and skimming this forum I cant find an answer to my particular problem. I know that a common reason for my circle problem is backlash and loose Gibb strips, plus possible play in the spindle.  I am used to the machine and adjusting it to eliminate play and it may be a red herring this slowing down of the Y axis motor but I have much to learn in regards to the software. Its frustrating as when cutting anything with no circle it performs brilliantly. I have thought of using it to change tool for a centre drill and spot where the circle should go, then boring on the lathe, or even using a boring bar (just thought of that Hmmm....) but that is not the answer. I want it working properly and I am doing something wrong.

Hope you can help...

Mike Freeman Brixham, UK

7

Mach4 General Discussion / Re: New people welcome !! Come in here and introduce your self!

« on: October 14, 2013, 07:54:00 AM »

Hello, my name is Mike Freeman and I am new to metal CNC. I have a RF25 round column Milling machine and have recently converted it to CNC. I have fitted ball-screws to both X and Y axis. I have CamBam, Mach3 , Cutviewer and Alibre 3D cad.

18 months ago I built a Sumpod 3D printer and spent some months learning how to print. It was this experience (and poor health) that convinced me to convert my mill to CNC. The mechanical side caused few problems and I checked the web for various issues I had at that stage.

I am covering the conversion on 2 websites I have www.mike@mikes-models.com and www.mike@mikes-models.com/blog

I am a retired firefighter (retiring from Bedfordshire and Luton Fire and Rescue Service) and now live in my home county of Devon (more specifically in Brixham, part of Torbay South Devon).

I have just registered as I am now at a point where a problem that my research has failed to resolve but I will list that in the right place.  I look forward to being part of this forums community.