mini grinders

I have gone through two Dremel grinders and a cheapo lookalike in three years. The Dremels failed due to speed control burning out and the motor burning out on the second. The cheapo gearbox fell to bits.

I don't use them heavily and only occasionally. Thought I'd treat myself to a Proxon, read a lot of very good reviews, not seen a bad one.

Having got one and used it for light sanding it suffers the problem of over heat. Gets very hot very quickly. Too hot to hold in a matter of minutes. Don't know how long this one will last. I've come to the conclusion that there isn't a good make out there.

Four of these tools in trouble suggests severe bad luck or they're being pushed too hard for what they are. What do you mean by "I don't use them heavily"?

My Dremel shows no signs of distress, but it's only used once or twice every few months for relatively light duties - cutting and polishing small parts etc. In my workshop 10 minutes 'at it' with the Dremel is considered heavy use, and then I let it cool off for at least 10 minutes before starting again.

The industrial equivalent has a separate motor spinning a chuck on the end of a bowden cable-thingy. The motor is considerably bigger than the one in a hand-held Dremel. Watched a stone mason using the same sort of tool except his was driven by compressed air - no risk of overheating but it wasn't half noisy!

Dave

I have had my Dremel for 5+ years, is used regularly and still works OK but it is only used for light work with cutting wheels, small grinding stones and polishers. For heavy work I use a 450W electric die grinder.

Same here my Dremel mostly gets used to tidy up castings, first lasted 10yrs or so and the current one is 4-5yrs old.

If your needs are heavy enough to wear them out or make them hot then maybe a commercial electric die grinder would be a better option as your compressor won't be up to powering an air driven one. The Makita ones are good but should be for a bit over £200.

Most are only 4 cfm. Even screwfix’s 100mm angle grinder quotes only 4cfm (but likely a bit of a joke).

JasonB:

I've been eyeing up the Makita range of corded die grinders and notice that one at least is stated to be "slow speed". Have you any comments as to the relative merits of these as opposed to the normal 24,000 RPM or so?

I replaced the speed control on my venerable Dremel last year for £3.83 with a pattern part from China bought on eBay. Works well except for the RF interference.

Ega Which one were you looking at I was thinking of the 24-29K rpm ones like this

NDIY The Screwfix 100mm angle grinder is shown as needing 170lts/min, that's 6cfm. Die Grinders are a bit less.

Sorry, it was the Toolstation one at a mere thirty quid which quoted 4cfm.

JasonB:

There's a 7000 RPM model on the same site:

https://www.lawson-his.co.uk/makita-gd0811c-750w-8mm-die-grinder-7000-rpm-gd0811c

I suppose that the relatively slow speed will allow larger tools to be used but be too slow for efficient cutting with the smaller sizes.

Yes that's for larger dia tools, not that fast if you are using smallish carbide burrs or stones. Probably similar motor speed but with a gear reduction to keep the torque high rather than the others which are variable speed so would loose a bit of grunt with a flap wheel or similar when run towards the bottom of their speed range.

Never used one but a pencil type air powered die grinder might be an option, maybe they don't use so much air as the standard sized ones. Very fast and not too expensive if you already have a compressor. I noticed this one in MSC's last advantage sale:

Jupiter Micro Die Grinder

William.

I use one of those pencil type air die grinders. Cheap ebay job. Works really well, and I've given it some abuse. 30 to 50k rpm if I remember correctly. Doesn't use much air at all.

Posted by William Chitham 19/05/2022 18:55:52

Never used one but a pencil type air powered die grinder might be an option,
maybe they don't use so much air as the standard sized ones. Very fast and
not too expensive if you already have a compressor. I noticed this one in MSC's
last advantage sale:

Jupiter Micro Die Grinder

William.

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This is the same pencil grinder from J&L ,runs through an air
pressure regulator at 90 psi from a 2 HP 25 litre tank compressor.
Compressor will cut back in after about 2 to 3 minutes to keep it running .
Same sort of pencil grinders from Aliexpress from about £12
and free delivery.

John

I got tired of burning out Dremel's.

They are only good for extremely light work.

I guess I burned out 3 of them.

I finally broke down and bought a tool-and-die grinder (photo below), and a carbide bit set.

It is rather a beast, and you have to really hang onto it, since it won't stop of you happen to snag it on something.

It works very well, but it is much larger and heavier than a dremel.

It really comes into its own when I use a 2" rotoloc sanding disc, followed by a 2" ceramic sponge.

The work you can do with it using the sanding disc and sponge is impressive.

It won't burn out even under heavy load.

Don't be fooled by the photo, it is big.

Edited By PatJ on 20/05/2022 02:45:08

I have the identical die grinder and needs both hands to hold it and the motor will not stall when taking heavy cuts with a 12mm dia. carbide burr on the edge of a 12mm thick steel plate.

Like other cutters, rotary burrs come in different grades and it is worth paying a bit more for a quality carbide burr that will remain sharp under use.

Edited By Paul Lousick on 20/05/2022 04:38:35

John P:

Is that a Quorn spindle in your photo?

I have seen some which claim to stop if they sense a jam.

Posted by ega 20/05/2022 10:59:48

John P:

Is that a Quorn spindle in your photo?

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No, it is 1 of 3 spindles made for this machine as internal
grinding spindles ,this one has a Quorn nose and can use all of the
Quorn wheels that i have.
Similar construction to the Quorn spindle but slightly larger ,uses
17x35x10 mm bearings .

John

I've got one of these: KATSU Die Grinder Variable Speed 6mm 320w (aimtools.co.uk)

for the price is great doesn't get hot at all

the same company do this as well: KATSU Electric Straight Die Grinder 6mm 101730 (aimtools.co.uk)