The versatility of advanced laser cutting techniques...making rigging blocks, an experiment

[Chuck]

Yes CNC and 3d printing has its advantages.  But laser cutting at an advanced level can produce some excellent results with some creativity.  
 

Below is an experiment of mine I would like to eventually translate to cnc.  But as you can see you can achieve shapes and details with a laser cutter that most wouldnt have guessed.  The double blocks below were entirely laser cut. 
 

In fact these are laser cut using just Yellow Cedar.  The color is all the laser char.  A quick dip in Ebony stain and you have some really nice blocks.  The laser cutting was done all four sides.  Pushing the limits of the machine.  Four of these little sticks took about 7 minutes or less of actual laser cutting.  Thats not bad for 24 pretty acceptable double

blocks.
 

i would like to apply this same technique to the Hobby CNC machines out there and see if they cross over.

 

[Jack12477]

Wow ! Those are outstanding looking blocks. 

[PRS]

Wow that looks fantastic!

 

Did you have to turn it over after each cut pass? How do you keep things aligned if you do?

[Chuck]

Kind of...but its a bit hard to explain.  The thickness also changes.  Like I said its pretty advanced.  It would take a few pages to explain and only those with laser cutters would know what I was talking about.   The blocks are 3/16" wide and 5/32" wide.  Single blocks are the same 3/16" width but only about 3/32" thick.  So its more elaborate than just flipping and registering. Lots of jigs but once set up you can bang out a ton of them quickly.

 

 

[Chuck]

The issue with this technique  for making blocks is all the char.   You cant throw them in a block tumbler to clean it all off.  That would destroy the shape of them.  This is quicker than how I make my regular blocks and the shape is more consistent.   But once you over tumble them to remove the char they look awful.  Even  if made from boxwood.   So this is a great technique however for those who want to stain their blocks and even ebonize them.   Then you dont have to tumble them at all.   Those fancy Ebony blocks you see for sale are so expensive.  But you can have some just as nice if you dip these sticks in Ebony stain or black ink and let them dry.   They polish up beautifully.

 

 

[Jim Rogers]

I have some great ebony stain sooooo

 

[grsjax]

Lovely blocks.  The char doesn't seem to be that bad and as you say a dip in stain or ink takes care of the problem.

[BenD]

Those blocks look really nice. Is it possible to round the sheave more with the laser? 

[mtaylor]

Just amazing what you're getting out that laser cutter.  You just pushed the envelope a lot further in the laser world.

[wefalck]

Well, I missed this thread since last summer. Don’t have a suitable laser-cutter, but thought by adding a 4th axis, i.e. an indexer, and modulating the laser power, one could do exactly that … You don’t have to worry about breaking milling cutters and could down to dimensions, where it would difficult to find suitable cutters. I am thinking of 1 to 2 mm blocks …

[Chuck]

I have been combining both types of mfg and these 2mm blocks have the sheaves laser cut and then the blocks are cnc milled to shape after the fact.   This gives you the precision for small detail as well as the clean milling on even the smallest parts.  I just took these pics with my phone so they are a bad pics but I found if you use bot CNC and a laser it produces the best result in a fraction of the time.... These are just 2mm long if you can believe it.   They were really hard to make and it took many failed experiments to get to these.

 

 

And here is a shot of some larger single blocks along with those tiny ones using the same exact process.  These are some pretty tiny examples.   I am refining the process as I gain more experience as well.   The issue with just a laser is all the char which is very problematic.   This gives you the best of both worlds and really cuts down on the cnc time which takes forever.  CNC is very very slow.

.

[Justin P.]

I still cant even work out how you do this with just a mill...   whatever secret genius sauce you re using, its working!  So cool.

[Chuck]

Thanks Justin….there were so many failures you didnt see.  I know my way around a laser pretty well and can push it to its limits.  But it isnt ideal for many applications. 
 

The cnc machine I admit I am still clueless about.  I managed to fumble through it and take what I know from laser production and just apply it to coming up with production approach on the cnc.  
 

The cnc machine is not a very expensive version.  Its a simple 3018 like so many of you guys have as well.  I have two now and they cost about $450 each.  A far cry from the $5000 a decent laser costs.
 

you can do some really good stuff with these entry level cnc  machines.  The learning curve should take 6 months to a year but i have figured out how to make decent blocks in just 3 weeks.

 

its all about the correct bit/endmill and speed and depth of cut rates.  A ton of trial and error really and a willingness to screw up and waste wood…time…and broken bits.  I am sure I can refine it as I learn more.

 

A look at a failed experiment….Notice how slow it is.  I can make the absolute perfect rigging block but it would take 4 hours to make 42 blocks.  Using the laser and the cnc and simplifying it….I can make the ones you see in that photo at a rate of 100 blocks per hour or so depending on the size.

 

Multiple passes….changing bits with each pass and flipping the board to repeat on the other side.  Its actually fun learning….and failing too.

 

[wefalck]

I gather you’ve used some kind of jig that allows you to zero-in each, the mill and the laser, for the consecutive operations. I understood that you index the billets manually in order to mill the four sides, correct? The milling wouldn’t be difficult with a ball-nose mill. Laser-cutting the sheave certainly lets you go down one almost order of magnitude in size.

[Chuck]

Yes that is it exactly.  The issue with the bits are the quality.  Even buying expensive bits they are not centered or not sharp.  Yes the tricky part is zeroing it out and getting everything all lined up.  Its tricky.  Whats even trickier is the fact that no two cnc machines are alike.  
 

There are slight variations between my two machines and no amount of calibration will sync them up.  So each machine needs different files slightly tweaked to help line everything up.  

 

If you are off by the tiniest fraction you screw up hours of work.  The jigs need to be perfect.  The machines need to be perfectly “homed” with each bit change and flip.  
 

It takes practice…especially on those tiny 2mm blocks.  Ball nose bits dont work on blocks this tiny. They break instantly and blocks fly across the shop.  For these tiny blocks the best bit is by far a “V” engraving bit with a 10 degree angle.  Remember we are only talking about wood that is 1mm thick and you are only milling through half of it with each pass.  Engraving bits are great for them.  
 

But even expensive “V” bits are crappy.  I have to trash half of them before I find one that works.  Nothing worse and more destructive than an off-center dull engraving bit.  Even the so called expensive bits are junk.  So I now buy them 30 at a time and throw away half of them.  Many have the tips broken right out of the box  new.  I test them all in the spindle and if they wobble I toss them.
 

 

Larger blocks and parts are different.  Those need roughing passes to remove the bulk of material before using the smaller bits. 
 

 

[Jaager]

Chuck,

 

Thinking about your char problem, I have vague recollection from Chemistry that there is one liquid compound that will dissolve elemental carbon.  I did a search to see if I could find out what it was and if it was practical.   No joy on the solvent, but I did read that in some situation acetone would displace a carbon deposit and suspend it.   I wonder if shaking the charred blocks in acetone would make them a shade or two lighter.  Then perhaps expose to Walnut husk dye would give you another color option.

[Jaager]

Just now, Chuck said:

The issue with the buts are the quality.

I have been up and around  RioGrande   https://www.riogrande.com  exploring the use of GRS gravers as carving tools and found that they sell a variety of bitts with unique profiles.  Their products seem to be excellent quality and the sizes are in our range. If you have not checked them out, it may be worth a visit. 

[wefalck]

OK, as I am not going into commercial production, I am staying with my shop-made manual mill - but laser-shaping of the sheave would be nice.

[Chuck]

I love my sheerline.  I made my old style blocks by hand using it.  I was able to make twice as many blocks per hour and sometimes more by hand.  But that meant I had to sit in front of a machine to make 2000 blocks.  For you….just making them for one model would be a walk in the park and I would also make them hand if that was all I had to make.  I agree with you that is the way to go for a guy just making blocks for their own models.

[Justin P.]

21 minutes ago, Chuck said:

But that meant I had to sit in front of a machine to make 2000 blocks

I cant even imagine this...     Im sure it will be well worth the effort if only it meant that you could only automate half the process.