I stumbled upon this youtube video looking for a new way to hold my wooden workpiece in place without leaving any marks or using screws. Anyone here having expirence with this method?
In basics you use masking tape (that is made to not leave any marks) together with CA glue (that is very strong and have no flex that you can have with double sided tape).
There are literally hundreds of fixturing methods for CNC… and more being invented all of the time!
In general, I despise any method that uses tape or wax - they create a mess and gum up my expensive end mills. Also, cleaning the end mills (and sometimes the bed) after using tape or wax seems to either get me cut or accidentally dull the end mill. YMMV.
I’m not to happy about using cyanoacrylate in a fixturing method, mostly because of the increased danger of exposure to skin and eyes. Removing cyanoacrylate from skin often uses compounds that are toxic. YMMV.
Any fixturing method that works well for you is good… it gets the job done. I can’t speak to the effectiveness of this method.
If I absolutely had to use tape, I used 3M #410M with success. I haven’t used tape in so long I can’t remember that last time I did. YMMV.
I would rather have a bed that allows me to fixture my stock creatively and not depend on tape, wax, or glue. YMMV.
A sea-of-holes, T-slot bed, and T-Track bed are the the methods I prefer - using mechanical fixtures to ensure stock doesn’t move. Vacuum beds, if the budget allows, is definitely nice - but are pricy, noisy, and often only effective on relatively large parts. I designed a vacuum hold down for small(er) parts on a machine without a vacuum bed - worked pretty well - but even that had its limits… The stock has to have sufficient area to be held in place with the available vacuum.
Vacuum holding can do some amazing things if one can do it. Some complex optics are polished (machined now-a-days) using vacuum holding!
I had a student who is a luthier and we made all of the parts with no tape or wax. Because they were on a budget, we did not have a vacuum bed… but we did have a T-Slot bed (a sea of holes would have been fine too but the CNC machine in question didn’t have one).
In this case, the bed was solid, with T-Tracks mounted to it. We cut spoiler board material strips to go in between the T-Tracks. The T-Tracks were then significantly recessed from the top of spoiler board pieces. The spoiler board pieces were mounted to the bed via screws and could be almost trivially replaced - the screws were nylon and the heads were recessed via a Forstner bit.
The CNC machine in question allowed the limit switches to be disabled and the machine had an actually work volume that was 1 inch larger than the bed in X and Y when this was done. We machined the top of the bed flat and square to the machine via a spoiler board clearance tool.
Now the luthier could use the amazing selection of T-Slot fixtures to hold their stock in place with no tape or wax. Most of the time, T-Slot clamps were all that was necessary. Everything, including the sound board, back, neck and internal parts were made on the machine.
The sound board was intentional cut every so slightly thicker than necessary. This allowed the master to impart his spirit to the instrument via hand sanding and tapping.
I would have much preferred to use a vacuum table for the sound board but, alas, no budget for it… so we got creative. The sound board was held using construction tabs… these were removed by the master via the sanding and tapping portion of the work flow.
mark
I use painter’s tape and it works great. Painter’s tape is easier to remove and as long as you have enough surface area it will hold just fine.
I also use painter’s tape between some plastics and carpet tape because the carpet tape is so hard to remove from some surfaces.
I know this thread is a bit old but I found it looking to see if anyone else had tried this method. For me it works Extremely well!! As long as I use proper measurements I never have my end mill touch the tape so no concerns on the gumming up my end mills from my perspective. I also do not use the super glue accelerant, I just buy quick setting super glue and use a little patience before cutting. Either way, if you haven’t tried this, and are curious, its worth a try IMO.
Other video on this method.
Happy DAY!
I’ve been using blue painters tape and CA for holding 12in X 24in sheets of fiberglass and carbon fiber for a while now. Works great and is much much much easier to clean up than double-sided tape. The tape can easily be placed only along the edges of the material and the cutters never come in contact with the tape. Even if it did, the adhesive is much milder than the adhesives used in double-sided tapes and doesn’t gum up my cutters.
I’ve been using wide masking tape on the waste board and bottom of the work piece and short bits of double sided tape in between instead of the super glue. It’s working well.
Oh nice tip, I’ll have to try that next!
I use a Low-profile 6" drill press vise.
I dialed it in using a indicator, and it works perfectly!! (I had to modify the mounting plate on the machine)
here’s my vise in action:
I run pretty low profile parts, usually in the .125 to .180 deep range, so this vise does the job.
I have also been using 3M painter’s tape with super glue with 100% success. Adds very little thickness to the stock, accommodates strange stock shapes by default, allows for cutter access to the full top surface of the stock (and down the sides), and is very easy to remove. Certainly a good option to have in the workholding bag of tricks.
I have tried every method for holding down stock that YouTube can offer. I have landed on the 3M Painter’s tape and CA glue from Rockler with spray activator. OMG it works good. I never have to leave tabs on profile cuts and it only takes a couple of minutes to remove tape.
PROS:
CONS:
I’ve been using tape/ca for awhile now with great success. Curious, what’s the point of “activator”?
The activator is a spray can of stuff you spray on one side to make the glue almost instantly stick. It is optional since most CA glues dry in about 5 to 10 seconds. At Rockler they have both the CA glue and activator.
https://www.rockler.com/search/go?ts=custom&w=stick%20fast
Example of some guy using the activator
I don’t find a need for it. Typically I can apply CA glue, put part down, get my endmill in, and it’s cured. It usually takes longer for me to get my program set up with the right endmill and my probe out so activator doesn’t gain me anything.
I think to make the whole process a little more stressful.
I like those few seconds of work time.
Thanks @The_real_janderson and @neilferreri.
Thought it’s use might be redundant in most circumstances. Maybe useful if you only have thick/gel ca on hand?
Generally speaking I use BSI insta-cure.
How much do you guys aim to cut-through the workpiece, when using this method?
Say I’m cutting some material that is exactly 4mm thick, would you zero off the top and then cut to 4.1mm?
Tips/tricks/what has worked for you would be appreciated.
If I define my material as 4mm thick, I set my bottom layer of tape as -4mm.
A successful cut is one that leaves the bottom layer of tape unscathed.
Oh man, I am much less discerning. I just add a generic 0.04" or so to my stock and cut through it into my sacrificial board below, but I just started cutting aluminum, and that is a carryover from when I cut wood exclusively. Habits are hard to break.
I’m rarely “successful”, but it does ensure I cut through. For aluminum, I always zero at the top on profile cuts. For wood, when I cut through, I just go by the wasteboard. If I cut too deep or too shallow on the first pass, it’s ok.
Gosh, I dislike it when an old thread is dragged out of retirement. It always presents the very first post, and it takes me a post or two to catch on. 
Why not just start a new thread with some personality? 
IMHO
Anyway, my tape and CA glue is my onion skin! 