Burned Out Dremel 4000

Results 1 to 6 of 6

Thread: Burned Out Dremel 4000

  1. #1
    Registered
    Join Date
    Dec 2013
    Posts
    3
    Downloads
    0
    Uploads
    0

    Default Burned Out Dremel 4000

    Short story:My dremel smoked up and doesnt start after trying to surface particle board in 1 1mm pass at ~30k dremel rpm. Machining time was around 40 minutes with a break in the middle to cool down.
    Setup overview: 7x7 zen, stock leads, 4000 dremel spindle, using a dremel 5.5mm cutter with 10 flutes, LinuxCNC and TB6560 board.


    Long Story:
    I have a 7x7 zen machine and cut only foam on it since I had the machine until yesterday. I wanted to cut out a surfboard fin cad model I made in freecad with wood. My first step was to replace my foam "spoil board" with a harder spoil board. I cut out a rectangular piece of particle board that covered the cutting area of my machine(200mmx160mm). I wanted to try and surface It since it seemed a little higher in one corner then the other and the fin was going to be a 2 sided part.
    Using CamBam I exported a g-code file that cut a line in the center of the board and then worked outward in rectangles( I didnt really have a preference how I did it other then efficient cutter movement and CamBam gave me that the easiest starting with a rectangle drawn with its CAD features). My machine will cut foam reliably at 325mm/min(except the Z axis which I limit to 150mm/min) so that's the feed rate I put in knowing I could slow it down with feed rate over ride. I have a dremel 4000 for a spindle and the most I ever ran it was 10-15k rpm and mostly below 10k, but just testing how the dremel cut a piece of plywood by had I knew i needed to up the rpm over 20k. My cutter was a 5.5mm square dremel bit with 10 "flutes" on it. I started the cutting out at 325mm/min with the dremel around 25k-30k. The initial plunge into the material seemed fine and it started cutting okay. I was watching the particle board to see if it was burning and It looked to be browning in some spots. Since I didn't notice the steppers skipping I brought the feed overide to %110. This made the steppers start to skip pretty bad so I dropped the override down to %80 just to be sure it wouldnt get thrown off more and I would only have to go back and clean up a few mm of missed particle board since the machine lost its reference. I brought the dremel up between 30k-35k since I slowed the cut rate down. I could defintely notice the cutter getting hotter and hotter so about halfway through the surfacing I paused the cut and let the cutter rest for 20-30 minutes and cool off.
    The surfacing was going pretty poor from a machining stand point but I kept going just to see how it would turn out. I started the machining back up with the cutter cool again and let it keep going. Well a little while later with about 10-20% of the board to finish the dremel started to dig into the board and run downward till it burrowed and stopped. I hit the e-stop as soon as I could. Then smoke and a burning smell started coming from the dremel.

    After I took the dremel apart I found one brush in perfect condition and another stuck inside the brush slot with its spring clearly damaged from heat and coiled into itself. It actually melted into the plastic cap that holds the brush spring in place. I am sending the dremel back for repairs.

    I am just wondering since I burned the dremel out so fast that using it for cutting any wood is unrealistic or will it be possible if I just adjust my cutting feeds/depths and spindle speeds more conservative. I honestly was worried only about the particle board burning, skipping steps or the bit dulling from the heat and not thinking the dremel would fail. I knew I wasn't doing its long term life good by running it high but for one use within its "rated" speed I thought it would be fine. Again this is the only time I have done anything about 15k on this dremel and its only been used maybe 5hrs of run time if that across 2 years of owning it.

    Similar Threads:


  2. #2
    Member
    Join Date
    Feb 2009
    Location
    usa
    Posts
    6028
    Downloads
    0
    Uploads
    0

    Default Re: Burned Out Dremel 4000

    4000s are known for burning up, there was a recall on them, although you are pushing it.

    Sent from my G-Tab Quantum using Tapatalk



  3. #3
    Member awerby's Avatar
    Join Date
    Apr 2004
    Posts
    5728
    Downloads
    0
    Uploads
    0

    Default Re: Burned Out Dremel 4000

    That's why a Dremel is a poor choice for a CNC machine spindle. They were designed for intermittent light-duty hand work, not for the continuous heavy cutting a CNC machine requires. After a short time at max output, the plastic case deforms and the alignment is gone, with predictably disastrous results. If it was in your hand, you'd notice it was overheating, but on the machine you can't tell until it's too late. Replace it with something more heavy-duty - at least a trim router.

    [FONT=Verdana]Andrew Werby[/FONT]
    [URL="http://www.computersculpture.com/"]Website[/URL]


  4. #4
    Registered
    Join Date
    Dec 2013
    Posts
    3
    Downloads
    0
    Uploads
    0

    Default Re: Burned Out Dremel 4000

    Any suggestions on a model that would have a decent rpm range? The ones I've found seem to all be above 16k RPM. I mostly cut foam on this and that might heat the foam up too much.



  5. #5
    Member awerby's Avatar
    Join Date
    Apr 2004
    Posts
    5728
    Downloads
    0
    Uploads
    0

    Default Re: Burned Out Dremel 4000

    There are router speed controllers that will slow them down considerably. There are problems with doing that, though, including loss of torque and overheating. One solution someone here on the forum came up with is the SuperPID speed controller: www.SuperPID.com - Super-PID Closed-loop Router Speed Controller which addresses these issues. I haven't tried it myself, but it has an enthusiastic following, and a long discussion thread here. I think it works with most conventional single-phase routers, but you'd be best advised to ask them which ones are recommended.

    [FONT=Verdana]Andrew Werby[/FONT]
    [URL="http://www.computersculpture.com/"]Website[/URL]


  6. #6
    Registered
    Join Date
    Dec 2013
    Posts
    3
    Downloads
    0
    Uploads
    0

    Default Re: Burned Out Dremel 4000

    Looks like all the other options for a better spindle are just way too much money for this little 7x7 machine. I cant spend another 100+ for a trim router and then 150 for a super-PID on this little thing. I guess I would rather abandon this thing for anything but foam. Does anyone else have any positive experience with cutting wood or MDF on the Zen machines? what spindle setups do you use? materials you cut?



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

Burned Out Dremel 4000

Burned Out Dremel 4000