CNC - calibration issues for inlays


Results 1 to 20 of 20

Thread: CNC - calibration issues for inlays

  1. #1
    Member difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    671
    Downloads
    0
    Uploads
    0

    Default CNC - calibration issues for inlays

    This is puzzling to me... I can scribe a line on my spoilboard, move the Y axis 48" by command line, scribe a line there and it measures exactly 48". I can do the same with X and move 25.75" and the measurement appears perfect. I am using a tape measure because that's all I have for measuring that distance. However, I used 3 different tape measures by 3 different manufacturers and each one measures identically.

    But, and this is a big 'but' to me, if I am cutting a pocket it ends up being undersized. Same with an inlay piece - undersize. I can compensate in the software (Fusion 360) but I shouldn't have to do that. If I cut a 1" square for an inlay piece and specify a 1.006" pocket then the inlay should fit with 0.003" clearance all the way around - it doesn't.

    I understand different woods, grain is hard in some areas, soft in others, cutting with the grain, across the grain, etc., but generally a 1.006" pocket should be 1.006", not 0.993". And a square inlay piece that is programmed to be 1" should end up being 1", not 0.992". Also, it's safe to say that all I cut are hardwoods and they hold their dimensions better.

    With simple shapes like squares, rectangles, circles, etc. it's easy to make them fit. But when I need to do complex shapes - music notes, arcs, a deer or car - it's very difficult to make these fit and sometimes downright impossible.

    When I first calibrated the CNC after I built it I did all my calculations under 6" so that I could use my dial calipers. What I found is that I could get it spot on for a 4" square, for instance, but if I needed to cut something 48" in the Y direction or 25" in the X direction it was off by 1/8" to 3/16" and that's simply unacceptable. So I did it the other way - I made the greatest distances as accurate as I could get them figuring that the smaller dimensions would now be very close if not perfect (within tolerance for the machine, of course).

    I have a few projects coming up with multiple inlays in each, probably 20-30 inlays and they're all different shapes and sizes, so I need to get this right. Today I cut some test pieces using a bit that measures 0.123" - a downcut 2-flute spiral - and climb cutting a rough pass leaving 0.005" on the side walls. Then I followed up with a clean up pass in conventional cut to remove the final 0.005". I figured that should take out any flex issues on the bit and also compensate for different grain directions. The feed rate was 75 ipm so not very fast. I was more concerned about pieces being accurate than being cut fast.

    Inlays fit but are undersized -
    CNC - calibration issues for inlays-001-inlays-fit-undersized-jpg

    Measurements of pockets and inlays -
    CNC - calibration issues for inlays-002-pockets-inlays-measurements-jpg

    Using 2" as zero to test Y axis calibration -
    CNC - calibration issues for inlays-003-using-2-inch-mark-zero-test

    Moved 48" and this appears to be perfect -
    CNC - calibration issues for inlays-004-using-2-inch-mark-zero-moving

    Using 2" as zero to test X axis calibration -
    CNC - calibration issues for inlays-005-using-2-inch-mark-zero-test

    Moved 25.75" and this appears to be perfect -
    CNC - calibration issues for inlays-006-using-2-inch-mark-zero-moving

    Setup for X axis calibration -
    CNC - calibration issues for inlays-007-measuring-x-axis-calibration-jpg

    So how can I get these inlays and pockets to be correctly sized? This generally isn't affecting the Longworth chucks I cut so many of and it certainly doesn't affect plaques or signs. But I don't see how it can be right at the greater distances but off on the smaller distances. I also see this when I need to cut a larger hole to fit a dowel, say 1 1/4". If I specify the hole to be 1.260" to give a little clearance then what I find is the hole comes out 1.235" to 1.240".

    Help!!!

    David

    Similar Threads:
    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  2. #2
    Member
    Join Date
    Aug 2005
    Location
    United States
    Posts
    84
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    Hi difalkner, sounds like you are using a re-sharpened bit; at .123" diameter, it isn't inch or metric? Will your control software allow you to input a comp value? As a trial I would suggest making a full width of cut single pass with the bit in question at the depth of cut and feed speed that you normally use and mic the width of cut. If you don't have cutter compensation in your control, you may have to create a new tool to match the cut width that you measured for that particular tool.

    I thought initially that this might be an issue of cutter flex, but I believe you've covered that already. I couldn't.t think of anything else that might cause this.



  3. #3
    Member difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    671
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    No, Marv, it's not a re-sharpened bit. I just checked a brand new still in the package 1/8" bit and it measures 0.124". My Whiteside 1/4" compression bits measure 0.245" straight out of the package. In Fusion 360 I have specified the actual size of these bits, not the advertised size.

    I can cut a slot with the bit used for the inlay test and then test the bit in the slot - it is very tight, a good fit, so not like there's a lot of slop involved. And the inlay issues are with any bit I use so something is inherent with cutting pockets because they're always smaller than they should be.

    David

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  4. #4
    Member
    Join Date
    Aug 2005
    Location
    United States
    Posts
    84
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    David,
    Do you know if your inlays are bigger by the same amount that your pockets are too small? If this is universally the case, a simple solution might be to halve the difference between the the two, subtract that from the cutter radius and use the resulting value in the tool registry. Your predicament sound pretty strange. Hope you find a solution.



  5. #5
    Member difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    671
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    They are not, Marv. The pockets are typically a good bit smaller than the inlays. The real issue is that I rarely inlay circles and squares. I'll do musical notes, letters, arcs, car outlines, etc. and often there are islands within these inlays (musical notes, letters, etc.) that factor in so I can't easily just fudge the settings because then the islands don't work out as they should. Like I said, it is puzzling.

    David

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  6. #6
    Member
    Join Date
    Aug 2005
    Location
    United States
    Posts
    84
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    David,
    What about your tolerance settings? Is there a chance that by tightening these up (using .001 instead of say .01; I don't know what you are currently using) when programming you might get a better fit? Also, how are you pulling geometry out to generate tool paths? Are you offsetting the geometry for clearance? Might this be the source of the problem? I know all this may be a stretch, but I thought I'd mention it.



  7. #7
    Member difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    671
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    I have Tolerance defaulting to 0.001" which makes Smoothing 0.0001" on every cut I make. I'll post more on toolpath generation in a bit 'cause I just figured it out... I think!

    David

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  8. #8
    Member difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    671
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    Ok, found it!!! At least, my tests are now working as designed. I'll try some more complex shapes later.

    Here's what I found - I recall reading somewhere that there's a difference between 2D and 3D Contour in Fusion 360 and that 3D is more a finishing profile. But 2D works for what I have needed about 99% of the time and that's what I use. Plus, you can have tabs in 2D but not 3D. I'm not certain where I read/heard that but I couldn't find this again in a quick search so I'll look later. Backlash has been discussed amongst the folks I queried on this so I tested that, as well. It was very minor - 0.001" to 0.002".

    Inlay - For the inlay piece I used 2D Contour and my standard climb cut with 0.005" Radial Stock to Leave for the rough pass followed by 2D Contour conventional cut to remove the final 0.005". The inlays, while slightly off, have not been the issue; the pockets were.

    Pocket - I created a profile for 2D Pocket climb cut to clear the inlay pockets with Stock to Leave set to 0.005" Radial. I followed that with a 3D Contour conventional cut and no Stock to Leave plus selected Repeat Finishing Pass to clean up the sidewall. This makes the cutter go around the sidewall twice, so even if the 0.005" clean-up pass had any deflection the second pass around should take care of that.

    The pockets now measure what I have specified in F360, or as close as I am able to measure. The important thing is that now the inlay pieces fit with no problem. I even placed my 1" round gauge bar in the 1" pocket and it fit (snug, but it fit).

    1" gauge bar in pocket -
    CNC - calibration issues for inlays-008-1-inch-gauge-bar-fits-1-a

    Testing backlash -
    CNC - calibration issues for inlays-009-testing-backlash-jpg

    Fusion 360 measurement for random double curve I drew for test -
    CNC - calibration issues for inlays-010-fusion-360-measurements-jpg

    Actual measurement -
    CNC - calibration issues for inlays-011-actual-measurement-jpg

    All pieces fit as needed, no forcing, not a sloppy fit, just right for glue -
    CNC - calibration issues for inlays-012-pieces-fit-using-3d-contour-final

    Thanks to all for your help and suggestions! These are just test files but I certainly don't mind sharing them if you want to dive into the settings.
    David

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  9. #9
    Member
    Join Date
    Aug 2005
    Location
    United States
    Posts
    84
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    David, great to hear that you've resolved the issue. No doubt frustrating along the way. I haven't gotten into Fusion yet, but expect to soon. What prompted you to use a 3D toolpath to mill what would normally be thought of as needing a 2D operation? Thanks for sharing,

    Marv



  10. #10
    Member difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    671
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    Two things, Marv. One was that I had tried about every other setting, and two was that somewhere I read that 3D contour is more of or a better finishing toolpath than 2D contour. I have only used 3D contour a couple of times but have used 2D contour a thousand times. So there must be something different in the algorithm driving the toolpath and I don't know that I'll find out what that is but it sure made a difference.

    David

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  11. #11
    Member difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    671
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    We've been gone all day down to Natchitoches to tour a shop and a couple of galleries as part of our Woodworking Club we started a little over a year ago. Saw some really cool shop designed and built equipment, too - old iron!

    Anyway, now that we're back home I headed out to the shop to do a more complex inlay with my newly discovered technique. This is a treble clef about 7" tall and a lot going on for an inlay. I cut the treble clef and promptly broke it in one place so ignore that. I figured it would suffice for my test. I cut the pocket just like I did on the earlier simple test - 2D Pocket to clear followed by 3D Contour with two passes around the sidewall. It was snug but fit, so I did another pass on the sidewall with Stock to Leave set at -0.001" and now it fits just fine.

    Since I don't want to break it again I didn't press it into place fully but it does fit with enough room for glue.

    CNC - calibration issues for inlays-001-treble-clef-jpg

    CNC - calibration issues for inlays-002-treble-clef-scale-jpg

    I'll do some others later.
    David

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  12. #12
    Member
    Join Date
    Aug 2005
    Location
    United States
    Posts
    84
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    David, in another life, I used to program for a -0.005" stock to leave on a final pass on some bolt together joinery. Once assembled, you couldn't slip a piece of paper in the joint. Your -0.001" must be a pretty tight fit. Thanks for sharing your experience.



  13. #13
    Member difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    671
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    To clarify, Marv, the inlay piece is 0.003" smaller than the pocket and I took an additional 0.001" off that, so it's now 0.004" although there's no way I can truly measure that. Maybe with feeler gauges in some spots but this whole inlay piece is curved.

    Thanks!
    David

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  14. #14

    Default

    D' adjusting when using wood I do as a matter of course course is done what machine you are using. If I get it perfect it won't be once the weather, material or shape changes. It is the wood moving my friend. The male more than the female, but both do.

    As I think you may know I make inlays for a living, so again it is most likely not your machine, all mine do this for inlays. If I make a .5in plug my males are .5125 for a perfect fit on one machine, slightly different on another.

    Anyone can say I am wrong, but with so many machines and near 600 floor inlays under my belt I am saying it doesn't matter. If CNC is the hobby then strive for perfection, if the end game are the woodworking results then just know to test every project and that the male most iems has to be adjusted to fit the female, end of. Once I was resigned to that I never looked back.

    Last edited by dovetail65; 02-09-2020 at 03:17 PM.


  15. #15
    Member difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    671
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    Welcome to the forum! You do inlays for a living? That's cool but I don't even know who you are so, sorry, I wouldn't know that. Point me to your website because I would love to see your work.

    Oh, and add your first name to your signature line so we'll know what to call you.

    David

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  16. #16
    Member difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    671
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    Here's an update on the inlay testing using some Walnut and Maple. I had a few minutes this afternoon and cut a small circle, an arc, and a larger circle (think, portion of a Longworth chuck).

    All the settings were as I specified before but ignore the first set of pockets. No matter how much you 'know' what to do if you type the wrong values the pocket won't be the correct size.

    The pockets are 0.006" larger than the inserts and fit nicely (0.003" per side). I really could make it 0.002" per side but 0.003" certainly makes it easy to get the inserts in with glue. The pockets are 0.150" deep and I cut the inserts 0.1875" thick to leave a little sticking out for sanding flush. Also, I cut the inserts upside down so I don't have to clean up the tabs and the extra 0.0375" is enough that I can lightly trim them and the inlay fits.

    I glued these into place, gave a quick 5 minute French polish (2# cut, light amber color), and took some photos, so nothing elaborate but you'll get the idea. I'm pleased with the fit on these inlay pieces.

    CNC - calibration issues for inlays-001-arc-circles-inlay-test-jpg

    CNC - calibration issues for inlays-002-arc-circles-inlay-test-jpg

    CNC - calibration issues for inlays-003-arc-circles-inlay-test-jpg

    David

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  17. #17

    Default Re: CNC - calibration issues for inlays

    I don't use my first name on the forums, just dovetail65. I don't use my first name on Joescnc, not Instagram, not Facebook(I am all private), not twitter, festool fourm, etc I am glad to tell anyone my name in a DM though. This goes way back to when I was on the Festool FOG forum and had huge issues and though it is very simple to find out who any of us are, even where we live that left a taste in my mouth and I never used my real first name on a forum since. That was over 10 years ago.

    I know another DFaulkner on another site, I just now noticed you are Difaulkner, so my mistake.

    When I design inlays using Aspire I use a .003 offset as a general rule and never use their inlay function. Then for certain projects pockets I test to come up with the offset I need to make it the male and female fit. I did some metal(aluminum as a test)inlays and sure enough they fit dead nits on every time.

    Most of my work now is floor inlays so other than the lettering(a pretty fair amount it my niche) the rest of the parts are made more like a jigsaw puzzle than an inlay. Then the entire thing inlayed into a floor.

    And your tests look as good as it gets, perfect.

    This is still my favorite inlay, a 42" installed at a yacht club a few years back(I don't install inlays only make them). I am limited to what clients commission me to make them, I never made an inlay first to sell so many of them tend to be very similar over an over.

    Attached Thumbnails Attached Thumbnails CNC - calibration issues for inlays-1-pegasus-floor-medallion-compass-rose-inlay  
    Last edited by dovetail65; 02-09-2020 at 03:18 PM.


  18. #18
    Member difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    671
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    You do nice work! In Fusion 360 there is no wizard to do the male/female parts for you; you have far more control but you have to figure out each step. I guess that's the same way you're doing it in Aspire, manually.

    Btw, there is no 'u' in my name - we spell Falkner correctly.

    David

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  19. #19

    Default Re: CNC - calibration issues for inlays

    Quote Originally Posted by difalkner View Post
    You do nice work! In Fusion 360 there is no wizard to do the male/female parts for you; you have far more control but you have to figure out each step. I guess that's the same way you're doing it in Aspire, manually.

    Btw, there is no 'u' in my name - we spell Falkner correctly.

    David
    Thanks for the compliment and my mistake on the name again.

    Anyhow, I am assembling another FLA 4x4, working on it today.



  20. #20
    Member difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    671
    Downloads
    0
    Uploads
    0

    Default Re: CNC - calibration issues for inlays

    If you're assembling a 4x4 please start a new thread and post photos so we can see what you're doing. We like photos!

    David

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

CNC - calibration issues for inlays

CNC - calibration issues for inlays

CNC - calibration issues for inlays