DIY table saw cuts through anything, leaves no room for mistakes

diy_table_saw

Students in the BASTLI lab at the Swiss Federal Institute of Technology Zurich had been stuck using underpowered and unreliable saws for quite some time. The saws often got stuck while cutting through PCBs and were generally a drag to use. When group member [Mario Mauerer] came across a big and powerful brushless motor in his basement, he decided it was time to upgrade the lab’s cutting tools.

Along with fellow student [Lukas Schrittwieser] he built a test rig to see how powerful the motor really was, and satisfied with the results, the pair set off to build their own table saw. The enclosure was wrapped up pretty quickly, leaving the pair to source a power supply. Rather than purchase one, they built a 700w monster switching PSU to power their saw.

As you can see in the video below the saw chews through most things with the greatest of ease, but the students added a “boost button” to the saw just in case they need to run it at full tilt.

While we can’t exactly overlook the lack of finger and eye protection in their demonstration, it does look like a great little tool to have around.

Comments

  1. purduecer says:

    Safety glasses!

  2. hoooooooooooooooooooooooorj says:

    What kind of finger protection? I do a lot of woodworking and aside from eye protection, the only real protection you want there is a riving knife to keep the kerf from closing on the back side of the blade and causing catastrophic kickback…

  3. adamziegler says:

    What kind of blade is that?

  4. adamziegler says:

    found it: 10cm sawblade (coated carbide metal, 120 tooth)

  5. ouch. Their just begging to lose a finger

  6. Kyle says:

    I don’t know why, but to me, the idea of building a useful tool just seems way more ‘bad-ass’ than building something that is cool but useless. Nicely done. certainly beats using a hacksaw.

    “we can’t exactly overlook the lack of finger and eye protection in their demonstration”

    A lost finger just might provide the motivation to build a really cool robotic hand.

    Seriously though, googles. Please wear eye googles next time!

  7. Hackerspacer says:

    Uhh… needs fence / guard. Brake would be nice. Maybe a quick way to change blade height or blades. But ok… this more or less works.

  8. Hackerspacer says:

    Reminds me of the wood, yes wood bandsaw. Yes, you can do it. You probably shouldn’t. Wood is not a dimensionally stable material. It warps, absorbs moisture, etc.

    http://woodgears.ca/bandsaw/build.html

  9. Hackerspacer says:

    Nevermind, it has a fence. Needs a guard though to prevent / minimize material being thrown though.

  10. spag says:

    @Kyle, totally agree. All my favorite hacks tend to be useful in some capacity. Personally, I may make the case all fancy or add stupid LED effects, but the core functionality is there. Good work guys. Seriously though, eye protection O.o

    A cool feature could be to add a tach (maybe back-emf monitoring) and a controller so the saw could be maintained at an ideal (or settable) RPM. That would dispense with the boost button and probably increase safety (although I’d love to scream YOU’VE GOT BOOST POWER! while pressing the button).

  11. Greycode says:

    The saw cool, the idea cool, the cuts cool, not even a hint of safety equipment, stupid as a bag of hammers. This thing cuts nice clean cuts, the kind that if their delicate pink fingers ever come in contact with will surely cut with a nice clean cut, it looks as though they may not even know they are cutting delicate pink things until they start gushing blood.

    The bright side of this is, when they do cut their fingers off, the doctor will be able to put the fingers back on if they get to him in time. But the other side, when something they cut flies off into another delicate part, their eyeball, the doctor is going to have one hell of a time getting it out. Even when I use my carbide blade on my dremel, I put on glasses.

    Nice project, and I hope your insurance plan is the bomb.

  12. karl says:

    FYI: Last year I found the perfect saw for PCB’s – a small 4″ dimond blade wet tile saw –

    http://www.homedepot.com/h_d1/N-5yc1v/R-202065695/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

    I was able to find one at a year sale for $5 and the kerf from the cut is just about 1/16″ –
    Beats the heck out of using a hacksaw or a jigsaw.

  13. vonskippy says:

    They need t Steampunkify it.

    //kidding, just kidding.

  14. andar_b says:

    $5?!??!? Wow

  15. John says:

    If you guys saw the table saw I use on a daily basis, it would scare the crap out of you. BTW learn what a push stick is and start using it before you lose a finger.

  16. Tony says:

    No goggles (hey, just lean back a bit!), no guard, no riving knife, no emergency stop, no kickback protection, fence not used, no pushstick, no t-slot for a sled, no sled etc.

    There’s a reason why the tablesaw is the most dangerous tool in the workshop, they’ll figure it out one day.

  17. silvesterstillalone says:

    My first instinct is to throw insults designed to attack the manliness of everyone here. Production saw work by hand is a..well its a thrilling thing. But I’ll leave that alone out of logic’s sake.

    However this shall not pass:

    “There’s a reason why the tablesaw is the most dangerous tool in the workshop, they’ll figure it out one day.

    Posted at 4:12 pm on Jul 7th, 2011 by Tony”

    Nope. That prize definitely goes to the radial arm saw, or more affectionately known as a radical harm saw. I will gladly use other types of standard power equipment with no safety guards (aside from the obligatory glasses) but I wont go near a radical harm saw.

  18. biozz says:

    make sure to do a finger check before and after each run XD

  19. Ryan says:

    Blade guards are unnecessary and often get in the way. Unless you have a high quality aftermarket blade guard most of them are just plain unsafe and can interfere with the cut.

    I would always use safety glasses but other than that not being an idiot is the best way to avoid getting hurt.

  20. jh says:

    goggles… get stuff on you… use compressed air to blow it off… or take a shower after all the work. saws are made to cut/throw stuff… if you don’t know how to use it so that kickback doesn’t happen… don’t use it. I’ve used full size table saws, radial arm saws, chop saws, saws-all… worst kickback I’ve ever had was with the saws-all, trying (and eventually succeeding) to cut wood that was too big around. When the tip would jamb up and kick, it was a bit jarring, but I was prepared for it (no locked elbows). Remember to go slow and don’t rush and be aware of what you’re doing. This will keep you from loosing body parts.

  21. jh says:

    oh yeah… that’s a nice little saw for the small bits. I wouldn’t mind having one myself.

  22. Oren Beck says:

    Building from a parts bin- Hack Cred. LARGE brushless counts for even more cred. Building the PSU is a step up, or down if it’s a lower volt motor. Gotta keep a sensahumor about puns or we get too serious to enjoy all this.

    As for the safety comments, yes- crappy safety features have maimed and killed far more folks than gear lacking any pretensions of safety concerns.

    The primary safety device is the human brain operating a machine. Damned little I know of in safety bits will protect an operator from brain non-function for long.

    Now, some brushless systems reputedly CAN do that formerly mythical, non-destructive ~4Krpm>0rpm in milliseconds but the required power densities use numbers akin to federal debt math. Figuring out the energy in the rotating mass and calculating the inverse energy+ losses required to *STOP* that rotating mass will show some cold equations about stopping a saw.

    Seeing a Hackerbuilt “Safestop” type system or functional equal is the next challenge.

    http://www.sawstop.com/how-it-works/brake-activation/

    That $69 cartridge + some Hackersmarts might be be a better bet than the average “Bet Your Fingers”saw. Though having the motor simply lock up zero drama might be a better/cheaper fingersaver. That is, if the blade does not break loose..

  23. m says:

    The place this thing is installed at is ~150m from the (probably) best hospital in Switzerland, so if they cut off a finger, it’s not far ;)

  24. Chris says:

    I have to wonder if the reason they were having so much trouble with their original saw is because they were using the wrong kind of blade (HSS instead of carbide) and improper technique.

    Adding more power when you haven’t got the basics downpat may help you finish the job short-term, but it may also lead to a bigger accident long-term.

    It is a nice saw though.

  25. Olivier says:

    There is a “security” feature : “three warning-beeps from the motor before starting the blade” :-/

  26. Kelly Martin says:

    Dude, that tablesaw is a baby compared to the one I have out in my garage (it’s a 12 amp motor, or over twice the power of that cute little gadget), and it’s only a basic contractor saw. There are top-end saws (like the one Norm uses on New Yankee Workshop) that pull 3000 watts or more.

    And it has exactly the same set of safety features as my table saw; I haven’t had the useless guard on mine in years, as it would just get in the way for a lot of things, and makes using the stacked dado impossible. I wouldn’t mind a riving knife, those do reduce the risk of kickback, but the stupid guard and fence that come with most American table saws are useless and every serious woodworker removes theirs almost immediately.

    The comments about safety here also really belie a great deal of ignorance of woodworking tools. Table saws are dangerous, but (like any dangerous thing) can be used safely and effectively as long as you stay focused and don’t forget what you’re doing. (And having SawStop helps, too.)

  27. D_ says:

    LOL I can’t resist. “manliness”, wouldn’t assuming that those that brought up the safety concerns are men, be sexist? All in all a nice saw, but the lack of eye protection in a school setting is a bit surprising. My prescription eyeglasses have protected my eyes so many time, I couldn’t think about going without eye protection. Protected from brain farts, and the unexpected.

  28. Pete says:

    I’d say the most dangerous thing here is the operator in the video and not the saw itself. All power tools require a safety conscience mind and operating a saw without safety glasses is foolish. I’d say a face shield might be more appropriate here considering the things they are cutting.

    A riving knife is really unnecessary here as the material to be cut (FR-4) is stable. Riving knives keep materials like wood, which can sometimes close the cut back on itself, separated on the back side of the blade, thus minimizing kickback potential.

    The power supply and construction of the saw is quite impressive. Although, a ground (surface ground, not electrical ground) nut for the blade arbor may have been a better choice.

    I liked that they built a dyno to test the output of their motor. This leads me to believe they calculated the required power for their saw etc. which shows some thought and intelligence went into this build.

    Overall, great job. Wear safety glasses and use best safety practices so you can keep making new projects.

  29. Mikhail Bakunin says:

    You guys totally missed it. The biggest danger of this saw is the fiberglass dust. (Much different then fiberglass stands like home insulation). The pure, tiny, tiny dust particles are really bad for your lungs – really bad.

    You might not loose a finger, but you’ll still end up at the hospital someday….with cancer.

    Have fun with that.

    MB

  30. Alex says:

    There’s a vacuum connected to the bottom., Mikhail.

  31. SuperNuRd says:

    Funny how he thinks that leaning back andsquinting protects his eyes seriously iI question your ability to process right from wrong this was WRONG!!!

  32. haexn says:

    @D_

    If they weren’t men then isn’t it a complement?

  33. Sodor says:

    Look a new machine to sew fingers…

  34. Mythgarr says:

    @Oh so many “This is the way I do it” comments –

    While it’s true that many carpenters take the various safety guards off a table saw first thing, most are smart enough to use a push stick on any cuts that would put their fingers within an inch or two of the blade. Paying attention to what you’re doing is ALWAYS the #1 way to avoid an accident but I would think part of that would be to consider just how close your hand is coming to that blade and to consider using an easily replaceable jig to prevent a rather permanent accident.
    Also, safety glasses and probably at least a dust mask. They’ve got metal filings, glass shavings, and god knows what else flying back into their face. A vacuum doesn’t catch everything.

  35. Mythgarr says:

    Oh – and a really awesome hack! To put something like this together from scrap is very impressive. They even though to add a fence (that they seem to never use).

  36. A_Blind_Man says:

    @kelly

    well yes and no, yeah this saw is Alot smaller compared to a wood saw, but that is its purpose, to make very small “precise” cuts. And for that the motor that they have in there is quite large

  37. zacdee16 says:

    I think that they should add a foot pedal for control of the blades (variable speed). And maybe use a metal clamp specially designed to push objects across to avoid loosing a finger.

  38. Otacon2k says:

    @Pete:
    “A riving knife is really unnecessary here as the material to be cut (FR-4) is stable. Riving knives keep materials like wood, which can sometimes close the cut back on itself, separated on the back side of the blade, thus minimizing kickback potential.”

    Bullshit. Come on, if, at the end of a cut, there’s only millimeters of material left to hold both pieces together, nothing will stop them from closing in on each other but a riving knife. Not much of a closing is needed for kickback, just a hair, touch the blade and off it goes.

    Seriously, +1 for riving knife, +1 for goggles)

  39. Mac says:

    well appart from lack of proper protection (which are not dramatic when cutting FR4), the project interesting part is the PSU and inverter.

    But I think they must teach a little bit more cutting theory. They use a motor that is rated 10krpm@40v, with a 100mm saw (they do not provide the speed they use, just a guess from motor refs).

    This mean 3000 m/min cutting speed! This is insane.
    Max cutting speed for carbine should be closer from:
    50m/min in stainless or titanium
    100m/min in steel
    300-500m/min in aluminum
    around 500m/min in wood, fiberglass and al.

    Exceeding cutting speed only gives shorter tool life and dramatic tooling failure.
    Carbide is very brittle and you don’t want to see carbide shards flying a 200km/h.
    That’s why a riving knife is a must, it keeps the material out of saw sides.

    On a another note, it’s better to have a double nut for locking the saw blade, as with one it will screw itself when the saw cut at highest power, making removal a pain (and stainless is prone to seizing, making things worse).

  40. rbjacobs says:

    Okay, just forget about the safety issues here…

    They made their own inverter and power supply! That’s quite a big accomplishment!

    The reasons I would NOT do a hack like this are the effort and cost required, plus the availability of ready made and safe alternatives.

    But I bet they can turn the design into a wicked controller for a 4th axis on a CNC table.

  41. TacoStand says:

    Not wearing safety goggles is completely unacceptable.

  42. They will be smiling until a thumb drops on the floor..

  43. YEs, high speed cnc would be cool. Cncn speed competition!

  44. Tony says:

    @silvesterstillalone, do they even make radial arm saws anymore? Or are they just a US thing? (Never seen one in my part of the world.)

    And @jh, you’re an idiot. If you think a good grip can prevent kickback, well, good luck with that.

    The main problem with power tools is complacency, as the guy using the saw shows. “Hey, look how cool this is!”. You only need to be distracted for a split second for something to go wrong. Showing off in front of a camera doesn’t help.

    All you need is for him to be leaning over the blade to grab the bits he just cut, and be bumped by the people behind him. A guard would have saved his fingers, contrary to what the manly “I don’t need no stinking guard” posters are saying.

  45. Pete says:

    @Octacon2k
    “Bullshit. Come on, if, at the end of a cut, there’s only millimeters of material left to hold both pieces together, nothing will stop them from closing in on each other but a riving knife. Not much of a closing is needed for kickback, just a hair, touch the blade and off it goes.”

    If we define the kickback force as F=ma then you can see that a cut leaving a millimeter of FR-4 wanging off the side of your cut, if it does come into a “hair” of contact with the back of the blade, will not generate a force great enough to overcome the force of push through the cut. However, a properly sized riving knife would not hurt things here, it just would never come into contact with the FR4 material during the cut.

    The point of my comment was not to discourage the use of riving knives but, to point out there are other safety issues that require more immediate attention such as eye and lung protection.

    My knowledge of riving knives came from a conversation with a professional woodworker 2 weekends ago when I was using his table saw to cut some “stickers” that we were using to “sticker” http://ohioline.osu.edu/for-fact/0008.html some lumber we had cut on his saw mill. This is a video of me tentatively cutting on the sawmill. http://youtu.be/CwfPZNRoyf8 Although we didn’t discuss cutting FR4 on a table saw, we talked about how riving knives work and why you need one or don’t. He did not, at the time have one on his table saw but he pointed out he uses mostly stable lumber and a high quality blade that he keeps sharp. Even with my limited experience using table saws I can say that I could tell his saw blade was very sharp by the sound of the motor and feed rate I was pushing the material through. Also, I used a pushstick :)

  46. Techartisan says:

  47. Tony says:

    @Techartisan, SawStop would be great if its inventor wasn’t an A-grade 5-star a-hole.

  48. @ Mikhail Bakunin: Barely.

    Not enough is known about fiberglass dust inhalation. For the time being, the answer is “no”

    http://www.idph.state.il.us/envhealth/factsheets/fiberglass.htm

    http://www.woodpreservers.com/pdf/FiberglassPole_MSDS.pdf

    http://www.netwellness.org/question.cfm/65688.htm

  49. Otacon2k says:

    @Pete
    I am not sure if we mean the same thing here. I wasn’t talking about a cut leaving a millimeter of material at the side. I meant that, when the cut is nearly done and there’s only a tiny bit of material holding the two halves together in the front, then there’s a serious risk of the two halves closing in on each other behind the sawblade. Which could then lead to kickback.

  50. Oren Beck says:

    Safety is an overarching concept of risk evaluations and sane responses to those evaluations. One neat Hack on Cancer causing chemicals might be a Cancer Resistant Rat? That’s the point. Riving knives for stuff where there’s a risk is common sense. In the case of a TINY board compared to a 4X8 sheet of plywood, that knife may run into scaling factor issues. NOT to discount it’s value even on small workpieces, but to restate the TOTAL evaluation concept.

    By the most uberparanoid rules, those sharp corners on their saw’s table are a hazard. In the end game of such zero tolerance for any risk- all corners should be rounded,padded etc like Larry Niven’s “Puppeteer” aliens designed everything in their worlds.

    Butter Knife= OSHA approved Razor Blade..

    Except- Homo “Sometimes Sapient” has a very much split mind on some things in our lives. Radically oversafe or suicidally lethal elements in the same device at times.

    BtW- No one so far caught the glitch in my mention of SawStop. SS works by conductive detection of whatever flesh is endangered. Circuit board foil would instantly and financially painfully trigger that AL wedgie into the blade..

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