Hey /diy/, I'm trying to figure out if it's a bad idea for me to build/use a homemade rotary tool like in pic related, safety wise. I'm planning on using it to cut mdf boards, and pvc piping, nothing particularly strong. Assuming that I use gloves, safety glasses, do you think this is a bad idea, or am I overthinking this?
>>1017855
That on e pictured is very low power and low RPM. It would be quite safe to build and use. Operation would be slow. If you decide to use an AC/DC wall unit, make sure it has at least a 2 amp rating. When a motor stalls it eats up a massive amount of power (sometimes peaking at 90+amps for a normal battery-powered drill for instance). The motor used in that one most likely won't exceed 2-3 amps when stalled.
However, a high speed, high power unit using a blender motor requires more experience and skill to design properly and still be safe to use.
The plan was to use about 5-7V worth of NiMH batteries, which push out about 3A, for the power source.
Going to use wall plugs to connect the connect the motor to the drill bit.
Think this will be strong enough to handle small amounts of MDF?
>>1017874
>Think this will be strong enough to handle small amounts of MDF?
absolutely not
if you have a harbor freight nearby get one of those plug in rotary tools
>>1017874
Something that small will only be good for very light duty stuff. Like engraving or shaping wood, not for disc cutting.
The HF ones as >>1017883 refers to is the exact same thing as you see in >>1017855 They are just a small low quality motor in a shell. I think the type of motor they use is the same used in most hairdryers. They have a ridiculously low duty-cycle. Lower even than the variable speed Dremels.
>>1017855
>I'm planning on using it to cut mdf boards, and pvc piping
I wonder what the thought process here is; I've seen it before.
>i need to cut thing
>table saw? no
>hacksaw? nah
>shitty dc motor with an even shittier cutoff wheel? PERFECT
Don't fall for the meme, OP. Use real tools.
>>1017910
This is /diy/ not /buy/. Also, OP will learn about motors and such with a small cheap project like this.
Become a yard sale, flea market and Craigslist ninja and you'll have all the tools you need for cheap.
If you score one that doesn't run or runs poorly, many can be revived by cleaning the commutator and replacing the brushes. Ebay as well as online stores like ereplacementparts (home of good exploded views useful no matter where you buy parts) are great sources.
I now look for ugly grout covered tools used by tile and construction workers because the dust fucks the brushes so they replace the tool. Cleanup is typically easy and parts other than the brushes typically ain't hurt.
I'm now balls deep in angle grinders, recip saws, circular saws and other professional tools for chump change.
>>1017920
Brush replacement on a DeWalt grinder. (BTW those grinders are excellent and even our welding students couldn't kill them.)
https://www.youtube.com/watch?v=9Vj8RQg-We8
>>1017920
This is a good recommendation. I have many such tools I got for super cheap or completely free. Often times at the end of a job the contractor company throws out all the old tools for that very reason. So, you can score a box load of like $5k in tools if you're lucky.
>>1017918
When did I say buy? I made my own table saw, and it's infinitely more useful than a dremel. You can make a hacksaw too, if you want; look up old frame saw designs. The point is that a dremel is an inferior cutting tool that nerds gravitate to because of the low skill requirement, rather than spending the extra five minutes to figure out how to do things properly.
>>1017855
Its not a bad idea but unless you live in some eastern European shit hole is there much point?
I mean I can't stand dremels. I've got one which I use to engrave tools that are worth anything with my details. That's it.
They're always on offer and not all that expensive.
>>1017918
If op wants to learn about rotary tools and motors he should build something with a real motor. He could build a bandsaw.
>>1017920
This is a really good idea. I looked into second hand ones, and the issue usually seems to be a lack of charger, or dying batteries, how should I deal with those? Will wiring some lipo or nimh together be a good solution?
Alternatively, these are some of the larger motors I have, does this change anything about this project being likely futile?
>>1018033
I would, but I'm a little new to diy, and I like my fingers.
>>1018139
Most older tools use NiCD or similar batteries. They are almost always filled with sub-C size cells. They are very common to buy. Once you crack open the battery case it will generally be a temp sensor and anywhere from 6 to 20 sub-C cells soldered together. Each sub-C is rated for 1.2 volts. So a 7.2 volt batteries will be 6 cells. It goes up from there until you get to 24 volt batteries (20 cells). All you need to do is buy replacements and trade them out. I generally do a complete battery change out but sometimes its just a single cell or two that are failing in the battery pack. That said, they often are lower amp hour rated cells anyway. I generally use high capacity replacements. I can double the operating time (amp hours) of a battery pack for half the replacement cost of a new one.
>Will wiring some lipo or nimh together be a good solution?
If you want to make your own battery pack, sure. Just match the voltage of the motor, which is easy as hell with DC motors because they have a wide operating range, and go to town.
>I would, but I'm a little new to diy, and I like my fingers.
Scroll saw. Much safer. Great for making very sharp turns in wood. Can also be used with jig saw blades (like a Rockwell Bladerunner) if you do it right.
https://youtu.be/GlPYAvmM1dM
https://youtu.be/-KBzb2au1X0
>>1017855
>cut mdf
Use a good respirator when you do this, MDF gives off a lot of very fine dust and the chemicals used to bind MDF are not good for your lungs.
Also cut it outside if you can.
>>1017920
Yep!, I've picked up some killer deal from yard sales, my wood lathe came from one.
