CNC Hold Down Methods: Workholding and How to Clamp Material to Your Spoilboard

[@MarkLindsayCNC]

Excellent video, Corbin! I guess it goes without saying that sometimes there is no single "best" method. They all have their place. We just need to learn the different application that works best for the job we're getting ready to run.

[@CorbinDunn]

Thanks Mark! Yeah, it's good to have a lot of ideas in the work holding bag of tricks.

[@mikegoins5663]

Thanks. I learned something new. I liked the good and bad for each hold down.

[@CorbinDunn]

Cool, I'm glad you liked that part! I see a lot of other videos saying "this is the way to do things", and they really don't consider all the options where it might be bad. Of course...give me another year or two and I'll probably have some new ideas that I like better!

[@dominaspina]

Wonderfully informative video. Thank you for going through the pros and cons of each method. As a CNC beginner I get to benefit from all your trial and error.

[@CorbinDunn]

Thanks, I'm glad it could help! There's never one best way to do a hold down...and I still swap through all the different techniques for different reasons.

[@samrix5793]

I really like your videos and content!

[@CorbinDunn]

Thanks!!

[@maximazur4854]

Hi Corbin! Great video! I made a 100mm grid of tnuts that go through the spoilboard and the backing MDF, so I can tight any bolt lengths. Another great addition to my CNC router was to design an auxiliar spoilboard as a vacuum table: with a square grid, a hole in the center, a 3d printed adapter for my shop vac and a long gasket to close a perimeter. You should try that! Works like a charm

[@CorbinDunn]

Just the shop vac works for it, that is super cool! I should definitely give it a try. I also know small vacuum pumps are pretty cheap these days. A removable vac table would be really nice for a lot of the stuff I do. I also think my next spoilboard will be a combo of t-nuts and t-tracks; the t-nuts are handy for certain situations. on my PCNC, they would bottom out on the PCNC's table, which was a pain.

[@robertyack1661]

Great job. I'm about to pull the trigger on DIY ATC based on your video series. I have a 5x10 Avid CNC. You may be hearing from me, sir. Love your style of teaching

[@CorbinDunn]

I'm happy to help if you have any questions! CNC Depot has some great new ATC spindles.

[@Curtis-Randall]

This video was super informative! Thank you for going every method, it helped me decide which kind of bed to make for my cnc.

[@CorbinDunn]

Cool, glad it could help!

[@DavidBeede]

Love your videos. They're well thought out and executed, like your shop and woodworking! I was hoping you'd have a DXF file of your spoil board. Very generous of you to share your drawings and cut files, except I don't use Fusion, I'm a Vcarve and Rhino guy. I guess beggars can't be choosers and all that. I'll just have to draw it myself. Keep up the great work.

[@CorbinDunn]

Hi David! Yeah, it shouldn't be too hard to draw up the spoilboard in VCarve; really it is just about creating an array of holes for the dogs, and making sure they avoid the t-tracks. I think if I were to do it again I would just cut the boards on my tablesaw, and once everything was down just mill the holes for the dogs. I recently started using Rhino and Grasshopper -- they are great design tools!

[@RAPTORNailsStaples]

Great video! We (Raptor Nails) are a little partial to the composite nails method! 🙂

[@CorbinDunn]

Awesome ;) -- at some point I may get a composite nailer...a lot of people do seem to love them!

[@iderryan]

Depending on what I'm cutting, I can add a tool path for screw divots as the first cut. By doing this, I know that my screws aren't in the way of other tool paths. If I know the exact locations of my dog holes and t-track (because I have the file I used to create them in the beginning) then I can use those locations for nylon hardware. Mostly, I use maple, ash, or oak for simple bar hold downs. 0.75" thick, 1.25 wide, and 3-5 inches long. A slot in the center for the t-bolt, and then cut a rabbet on each end 3/8" square. This is super easy with scrap hardwood on the cnc, then just cut them to width on the table saw.

[@CorbinDunn]

Awesome - that sounds like a good method for doing hold downs, especially if you have a consistent size work that you do a lot. I know a lot of people do the layout file technique with VCarve that you are talking about, and it can work great.

[@bloho_design]

Another great video! I’m pretty scared about running into hardware so I’ve done nylon 1/4-20 hardware, and am lazy so will tap the hardwood for threads instead of embedding a nut (since I don’t want to use metal t-nuts..)

[@CorbinDunn]

Thanks, and nylon 1/4-20 hardware!! That's actually a great idea...I hadn't ever thought of it.

[@johnhadley6413]

Very well done

[@CorbinDunn]

Thanks!

[@braunproductions3254]

Love your channel. Since you are the youtube channel that most resembles what i would do with a router table I would like to know what you would order if you were to start over today? Basically tell me what to order from who and hopefully I can afford it and place my order right away. Thank you in advance

[@CorbinDunn]

Thanks! It's still not an easy decision on what to buy. I still go by a lot of the statements in my first video about the Avid CNC (link at the end). I still think that is a great machine and a good buy. In my use, I don't think I really needed an 8'x4' table; a 4'x4' would have probably been better, and I don't think I needed the high HP spindle I got. I'd maybe look more into the StepCraft series of machines with an ATC, mainly to get more accuracy and precision with a ball screw, but at the expense of not as much power or speed. In general, I don't cut too fast due to bad quality when doing that, so speed may not be as essential as I was initially thinking. I'd also possibly consider Phantom CNC's 4x4 ATC machine, however, shipping is still prohibitively expensive to California. An Avid CNC with a CNC Depot ~4hp ATC spindle is probably still a good option. Link: kzbin.info/www/bejne/jKS7mq1qo910fcU

[@braunproductions3254]

@@CorbinDunn I have watched that video. I guess i am asking for more details for what you suggest i get from avid and other companies when I order an avid 4x8. I plan on building my own Table Base and really want an ATC. Thanks again

[@CorbinDunn]

@@braunproductions3254 Oh cool - Aside from Avid's basic kit (minus legs, if you make your own base), get the RM 40 kit: www.cncdepot.net/products/newavidkits -- that's mostly it!

[@CorbinDunn]

Or RM40C, for higher RPM

[@KABATAPE]

I'm wet behind the ears, always listening for good advice, this was a great review and insight to the forces at play. I will purchase the 3D toe clips. The plywood stock I work with is always less than 0.75 and more than 0.65 Will the 0.5 clip suffice? or should I request a 0.625 clip designed?

[@KABATAPE]

The 3D printer operator says he can scale the clips, I think this should work. Print 2 sizes 0.6 & 0.7 and use 2 colors to differentiate.

[@CorbinDunn]

Hi! The 0.75" toe clamp is designed to have a bit of a gap..I think about 0.100 or so (adjustable in the Fusion 360 file). So, Print the toe clamp for the material height you want to clamp down, and it will work. smaller clamps can also be shimmed up (ie: 0.5" clamps can have a 0.25" shim to hold down 0.75" stock).

[@CorbinDunn]

Hopefully you don't have to scale them...just print the size you need, and custom sizes can be done easily in the Fusion file!

[@dangoras9152]

That's one way to use a body hammer 😂.. Good information brother I think I will stick to double sided tape.. Keep it up brother

[@CorbinDunn]

Haha..yeah! Double sided tape and the toe clamps are really all I use these days.

[@AndyBlackman]

The AirWeights Workholding System seems to be promoting itself on the socials lately. Kinda pricey. Looks interesting though. I think its is directed towards more production level workloads.

[@CorbinDunn]

I do recall seeing an ad for those a while back! I just googled it again, so I'm sure I'll be seeing more ads in the future (hah!). They do look nice, but pricey. I bet one could DIY the same setup for at least half the cost. The usual time vs money tradeoff.

[@ClintonCaraway-CNC]

PwnCNC sells toe clamps with square washers for reenforcement.

[@CorbinDunn]

Awesome! I hadn't seen the ones PwnCNC makes - they look similar and probably work great! The square washer probably helps avoid the flex issue that I see in the long clamps - that is a great addition! Their pre-made Toe Clamps at $13 are a pretty good deal. I talked with PwnCNC not too long ago about helping with some of their ATC stuff on Mach 4; they are some nice guys.

[@billysmether6237]

A vacuum will not hold down small parts. There is not enough surface area to create downward pressure. It can hold down a small part if it is connected to a larger base piece. I have tried them all. I screw everything to the machine bed (MDF). Super fast, super secure, and nothing for bit to jog into. Thanks for video!

[@CorbinDunn]

Awesome, that works! I've heard of some people making more specific small-part vacuum chucks -- some work for wood lathes..I might investigate those at some point and see how well they work for CNC

[@Pidalin]

Yes, we have morbidelli machines with classic vacuum pods and this is a massive problem for smaller parts and everything is extremely overpriced for these machines, like one vacuum pod cost like 320 eur and you need 10+ of them for some bigger plates, it's ridiculous. Our maintenance guy says it's because of it's made of some special plastics that is stable under heat and EU taxed it as dangerous material, but even alternative ones are expensive, I don't really believe it's the reason, they just know you have to buy it, so they want 300 eur for few grams of plastic.

[@ChinJazz]

Hi Corbin, First, a huge thanks for sharing all your methods for CNC hold downs! I'm a Guitar Luthier, and moved into the world of CNC to help with certain operations (1st "Employee").. Anyway, in my travels I discovered Temple guitars (Jayszun Vanderwerff)... He shared a technique with knotching corners and it puts downward pressure with regular t-track clamps.. Here's a video at the specific location to visualize: kzbin.info/www/bejne/fWaVgKttp7-aZqMsi=lc39Kwe0hXdi65Q0&t=95. This may add ideas to your tooling designing :) -> Pay it forward right? Now, I need to find someone to print me come of your Side Cam Claps!!! Any way, again, thanks for sharing! Cheers, Adam

[@CorbinDunn]

Hi Adam, Thanks! After I made this video I learned about the "notching" technique. That is another great way to hold down stuff without risk to hitting the tool. I'll definitely give it a try sometime. Look into getting a 3d printer: they are super handy! I have a Prusa, but I hear the Bambu lab ones are also great. (especially the X1-Carbon).

[@maddogtungate6740]

I don't understand how people seem to always run in to their hold downs when you can program the cnc to go above them.

[@CorbinDunn]

Yeah, for sure...I still do it by accident on occasion (like, yesterday, doh!)

[@Pidalin]

It depends, when you have oldschool programming, you can do a lot, when on newer machines with CAD-like software, you don't have that good control over it or it's much more complicated to do it. We have Morbidelli machines and with old Xilog Plus software, it's very easy to program it, you just put line for example Z=-100 at the end of geometry where you need to go up, for newer machines, it's not that simple. You can use command to reset spindle which also sends it up, but it goes all the way up, so it's too time consuming and it doesn't solve all cases. In oldschool programming, you can do much more complex things. I mean like, not program complicated shapes, but complex in how exactly spindle is moving and where it is going. Fortunatelly, for our vacuum pods, this is not such a big problem.

[@CorbinDunn]

@@Pidalin vacuum pods look awesome..I think they'd work great for the stuff I do, and I should look into them!

[@Pidalin]

@@CorbinDunn But it's extremely overpriced, one can cost like 400 eur for no reason.

[@cliffart7398]

The 1/4-20 you used is not a nut but a bolt. I have made mine out of wood.

[@CorbinDunn]

Making them out of wood is a great idea! No chance of hitting metal with a bit. I might have mixed up the words nut and bolt at some point...hopefully my point came through.