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Thread: Using a 4 1/2 in angle grinder on wood?

  1. #1
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    Default Using a 4 1/2 in angle grinder on wood?

    I need to remove some decayed wood to do a repair in a confined space (inside a locker, basically) where it is nearly impossible to use a plane and very hard to use a chisel.

    I would appreciate thoughts on using an angle ginder with a cut-off wheel in such an application. Most of the 4 1/2 wheels I see seem to be designed for metal. Can they also be used on wood, or are there ones designed just for wood? (I do not want to use one of those things that looks like it is wrapped in chain saw chain.)

    I would need to be able to cut as well as do surface grinding (sanding).

    Thanks,

    Brian

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    If it works use it. There are also little chain saw wheels for those machines. Aggressive but effective with care. I'd think of a scraper first.

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Yes.

    It basically grinds and burns its way through the wood, but it will cut it neatly.

    Just a couple weeks ago, I used an angle grinder with a metal cutting disk to cut out the cabin sole in my sailboat - I cut both plywood and fiberglass/resin with it. Wear hearing protection and a good dust mask, and safety glasses.
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    If you can get a couple of 24 grit discs and put them back to back,with no rubber back up disc,it works pretty well.
    The chainsaw wheels work great too,but the guard must be used to limit the cutting depth and aggression.
    R
    Sleep with one eye open.

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    There are also very coarse abrasive wheels available.
    David G
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  6. #6

    Default Re: Using a 4 1/2 in angle grinder on wood?

    I just LOVE my 4 1/2" angle grinder sanding machine, fitted with a sander backing pad and 36 grit paper. It is great for making short work of both wood and hardened epoxy. (Be careful as this stuff removes skin very fast too.) You need a rubber sanding pad attachment, like this BOSCH MG0450.


  7. #7
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    aka "Wood Erasers"...
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Sounds like a Fein saw blade would be better and safer for cutting. I use a disc sander in a 4 1/2 ins. grinder for lots of sanding, shaping, etc.

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    In confined spaces and wishing to remove surface deacay (i.e. not actually cutting out) I use a Fein Multimaster and a carbide rasp - it will eat it away and has the advantage of dramatically slowing its progress when reaching good wood; a 4 1/2 grinder probably doesn't give that kind of feedback. To tidy up I then use 6ogrit multimaster sanding pad.


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    Default Re: Using a 4 1/2 in angle grinder on wood?

    any working wooden boatbuilder has an angle grinder grafted to his right hand
    whatever rocks your boat

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Maybe this?
    Chuck Thompson

  12. #12

    Default Re: Using a 4 1/2 in angle grinder on wood?

    Quote Originally Posted by Paul G. View Post
    any working wooden boatbuilder has an angle grinder grafted to his right hand
    ...and Band-Aids on his left hand.

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    I do not know how to build or repair a boat without my 4-1/2" grinder! Here is a time lapse video of scarfing plywood with my handy grinder:


    The breaks you see me taking are to let the feeling get back to my fingers, lots of vibration.

    Dan
    Last edited by Auroradan; 03-14-2011 at 02:35 PM.
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Sure, go ahead and use one. Just be aware that they can do a considerable amount of damage to anything in their path if they get even a little out of control. This includes your own living flesh. You also really, really need to wear your safety glasses.

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Quote Originally Posted by James McMullen View Post
    Sure, go ahead and use one. Just be aware that they can do a considerable amount of damage to anything in their path if they get even a little out of control. This includes your own living flesh. You also really, really need to wear your safety glasses.
    In the tight space you are proposing to use the grinder, I would use goggles. Safety glasses at minimum, but flying crap gets behind them easily. Only get one set of eyes.

    Cheers,

    Bobby

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Isn't the angle grinder Erster's favorite precision tool?
    Steve Martinsen

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Quote Originally Posted by SMARTINSEN View Post
    Isn't the angle grinder Erster's favorite precision tool?
    In experienced hands... a grinder can be remarkably precise. Those hands aren't mine. I'm more fascile with a belt sander.
    David G
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Quote Originally Posted by Auroradan View Post
    I do not know how to build or repair a boat without my 4-1/2" grinder! Here is a time lapse video of scarfing plywood with my handy grinder:
    [URL="http://s156.photobucket.com/albums/t4/auroradan/BFD%20Brockway/?action=view&current=Scarfing3sheets02.mp4"]

    The breaks you see me taking are to let the feeling get back to my fingers, lots of vibration.

    Dan
    What abrasive wheel were you using?

    Thanks for the video!
    I love the smell of fresh cut plywood in the morning.

  19. #19
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Quote Originally Posted by Auroradan View Post
    The breaks you see me taking are to let the feeling get back to my fingers, lots of vibration.
    If it was vibrating that badly, then (1) I would say something is wrong - mine actually is pretty smooth. The thing that vibrates the most is the knotted wire cup. But a grinding, cutting or sanding disc does not. Check to make sure you've got that wheel properly centered (and that the center hole is the right size for your grinder!) and that the wheel is not damaged or out of round. And (2) that kind of vibration can actually cause a repetitive motion injury, like carpal tunnel syndrome or tendonitis. In short, it's not good for either you or the tool. Check it out and see if you can reduce or eliminate it - it shouldn't vibrate that badly.
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    One thing to watch out for is the speed (in revolutions per minute, RPM) that the grinder turns. A lot of dedicated metal-working grinders turn too fast for use with an abrasive disc glued to a soft backing pad, or even a fiber-abrasive disc. When these discs come apart they fling shrapnel with a lot of force.
    Right now I own eight different right angle machines, ranging from a little Bosch DA sander with variable speed, up to a Milwaukee 15 amp welder's grinder that is incredibly powerful, and quite dangerous. My favorites for close-quarters work are variable-speed types with hard pads and type C discs.

  21. #21
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    I use my 4.5 smallest Makita grinder with the attachments shown below (http://www.amazon.com/Makita-9554NB-...161393&sr=1-14 ). One is a stepped sanding wheel (80 grit) and the most aggressive... the other is a roloc adapter with a two inch sanding pad. The small red pad was $6 at Harbor Freight and screws right on the the 5/8-11 arbor of the grinder.

    I use these all the time in fiberglass and wood repair where I need to shape wood. The large deadeyes below were shaped as you see in just a couple minutes as easy as pie using the sanding wheel stepped as shown beside the deadeyes. Just let your wrist swivel and it was very easy.

    The smaller roloc 2" sanding pad is for smaller work as you can see I used it to bevel the plywood for the repair of the hole in the hull. The 3M Roloc adapter will allow you to use one inch, two inch, three inch and four inch sanding pads that utilize the Roloc twist on sanding discs.

    I have two of the smallest Makita grinders in the Amazon link above... and keep them both with the accessories shown for different jobs. The red 3" sanding pad is velcro for any hook and loop 3" sanding discs... and the stepped sanding wheel is available at Lowes or HD... both just screw on the 5/8-11 grinder arbor. The most aggressive stepped sanding wheel will easily cut through panels if the edge is pushed through.

    Good luck,

    RodB





    Last edited by RodB; 03-15-2011 at 12:05 AM.

  22. #22
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    I saw some photos on Goodle a couple of years ago where someone had posted about using an angle grinder in place of say, a backsaw. The photos depicted a breasthook and some quarter knees. The jointery was so perfect one could not tell where the lines were except by following the wood grain. I have searched since then and not found the site, but I didn't dream it...I did go out and buy one and I have found them useful, including for precise work. But I don't have enough use of one to get good with it.
    Last edited by davebrown; 03-15-2011 at 05:12 PM.

  23. #23
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Donald,
    It's a Harbor Freight Carbide cup wheel:
    http://www.harborfreight.com/power-t...eel-66613.html
    The sawdust it makes looks like what a Chain saw makes, very aggressive! Surly would mean a trip to the ER if it caught my skin.

    Dan

    Quote Originally Posted by donald branscom View Post
    What abrasive wheel were you using?

    Thanks for the video!
    Darwin
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  24. #24
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    It's not really vibrating badly, my hands naturally go numb after holding a tool for extended periods of time. I do alot of metal works and most days I have a 4-1/2" grinder in my hands. No matter what grinding wheel I use, hands still get numb.
    While cutting the scarfs, I did have a stronger than normal grip on the tool. Needed to so I would not cut away too much material.

    Dan

    Quote Originally Posted by ILikeRust View Post
    If it was vibrating that badly, then (1) I would say something is wrong - mine actually is pretty smooth. The thing that vibrates the most is the knotted wire cup. But a grinding, cutting or sanding disc does not. Check to make sure you've got that wheel properly centered (and that the center hole is the right size for your grinder!) and that the wheel is not damaged or out of round. And (2) that kind of vibration can actually cause a repetitive motion injury, like carpal tunnel syndrome or tendonitis. In short, it's not good for either you or the tool. Check it out and see if you can reduce or eliminate it - it shouldn't vibrate that badly.
    Darwin
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  25. #25
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Quote Originally Posted by seo View Post
    One thing to watch out for is the speed (in revolutions per minute, RPM) that the grinder turns. A lot of dedicated metal-working grinders turn too fast for use with an abrasive disc glued to a soft backing pad, or even a fiber-abrasive disc. When these discs come apart they fling shrapnel with a lot of force.
    Right now I own eight different right angle machines, ranging from a little Bosch DA sander with variable speed, up to a Milwaukee 15 amp welder's grinder that is incredibly powerful, and quite dangerous. My favorites for close-quarters work are variable-speed types with hard pads and type C discs.
    As I don't have them luxury grinders with rpm-adjustment, I made myself a little rpm controller to connect between the grinder and power connection/wall socket. Quite handy and not too expensive.
    When you're chewing on life's gristle
    Don't grumble, give a whistle...

  26. #26
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    The rolock adapter came from Harbor Freight?
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    The roloc adapter came from Ebay... do a search Roloc 5/8-11 1/4" adapter

    http://cgi.ebay.com/2-ROLL-LOCK-HOLD...#ht_1974wt_907

    Its solid machined steel witha female 5/8-11 on one end and 1/4-20 on the other

    The 3" plastic red hook and loop sanding pad with a metal insert 5/8-11 came from Harbor Freight

    I don't know if they still carry them now.

    R
    Last edited by RodB; 03-15-2011 at 08:30 AM.

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    In lieu of a bunch of expensive tools and even scarfing jigs, my angle grinder is standard fare along side of my car keys and empty wallet. Its even my on site mitre moulding tool too and I cut every single piece of trim of compound angles too. Its the only tool I use to cut scarfs in every single sheet of plywood. Most hardware stores carry the rubberized soft backing plate and the discs. I use almost exclusively the 24 grit for cutting rough cuts and use it to clean out areas which I have removed any bad wood. Sure it does not get too close to corners. But the die grinder attachment works for that even though the speed is a bit much for finish work without a steady hand or amateurs afraid of the right tool.




  29. #29
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Quote Originally Posted by Auroradan View Post
    Donald,
    It's a Harbor Freight Carbide cup wheel:
    http://www.harborfreight.com/power-t...eel-66613.html
    The sawdust it makes looks like what a Chain saw makes, very aggressive! Surly would mean a trip to the ER if it caught my skin.

    Dan
    Thanks Auroradan! I learned something new.
    I love the smell of fresh cut plywood in the morning.

  30. #30
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    In lieu of a bunch of expensive tools and even scarfing jigs, my angle grinder is standard fare along side of my car keys and empty wallet. Its even my on site mitre moulding tool too and I cut every single piece of trim of compound angles too. Its the only tool I use to cut scarfs in every single sheet of plywood. Most hardware stores carry the rubberized soft backing plate and the discs. I use almost exclusively the 24 grit for cutting rough cuts and use it to clean out areas which I have removed any bad wood. Sure it does not get too close to corners. But the die grinder attachment works for that even though the speed is a bit much for finish work without a steady hand or amateurs afraid of the right tool.
    Erster, thanks for your post. I use several attachments on my grinders but usually not the one you pictured, which I can see will come in handy for specific jobs. I tend to many times take the piece to my small bench belt sander/ disc sander... I always learn something from you. Thanks.

    RodB

  31. #31
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Round here we call an Angle grinder a "Canvey plane" as they were standard joinery equipment in the GRP yards on Canvey in the 60's & 70's.
    I have several & they are capable of accurate work. The most violent discs i have seen were grizzly discs 16 grit jobs with spiral grooves to shed the dust.
    One day i was grinding GRP on a big hull repair while using one of these on a 9" Hitachi grinder. At the end of the session i put the wheel down on my thigh. Fortunately i had just released the trigger. It being very cold i was wearing long johns, jeans, overalls & an NBC oversuit. That wheel ripped through the lot before it stopped. I had a 4" graze across my thigh that stung quite a bit. That 1700w Hitachi is the one machine that always scares me a little when i use it!
    One other thing, grinders kick up a lot of dust use a good respirator!!!!!

  32. #32
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    You didn't say what you were patching the rot with. If scarfing in another piece of wood,a plunge router is easily controlled in a confined space and makes chips not dust.

  33. #33
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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Quote Originally Posted by keith66 View Post
    Round here we call an Angle grinder a "Canvey plane" as they were standard joinery equipment in the GRP yards on Canvey in the 60's & 70's.
    I have several & they are capable of accurate work. The most violent discs i have seen were grizzly discs 16 grit jobs with spiral grooves to shed the dust.
    One day i was grinding GRP on a big hull repair while using one of these on a 9" Hitachi grinder. At the end of the session i put the wheel down on my thigh. Fortunately i had just released the trigger. It being very cold i was wearing long johns, jeans, overalls & an NBC oversuit. That wheel ripped through the lot before it stopped. I had a 4" graze across my thigh that stung quite a bit. That 1700w Hitachi is the one machine that always scares me a little when i use it!
    One other thing, grinders kick up a lot of dust use a good respirator!!!!!
    Yep, the angle grinder is no toy and it can bite you when you are careless. Some jobs are tough and call for a tool just as tough. I have three of them and have used them to sand gel coat off two keelboats. I also use a 4" one to shape small art work pieces held in one hand. Have learned to wear a glove on that hand though. The 16 grit disc is a bit scary but it can really get into the job when called for. The chainsaw tooth disc is great for hogging out hollows in chair seats and some use them for carving animals from stumps. For that it is at least safer than a chain saw. Like all such tools, use it with respect or it will not respect you.
    Tom L

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Thanks for all the info. Yes, I have respirators and eye and hearing protection. There is not enough room in this spot to use a plunge router (or even a regular router or laminate trimmer).

    Brian

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    Default Re: Using a 4 1/2 in angle grinder on wood?

    Aluminum boat builders use a carbide saw blade free hand in their mini grinders to cut out pieces. Very important to remember to always have the blade pulling away from you. had a mate forget this once and caught a kickback in the side of his face. Not pretty. We use mini grinders a lot. with skill they can cut very accurately. They can also cut flesh quickly. We were fitting an interior assembly to a glass hull. The assembly was the complete interior built of Tri-Cell for a 40'sort fisher. We suspended the part above the hull with a pair of gantries and lowered it til touching and marked where it touched and then lifted it back up and ground some. Repeat, repeat, until very close and then mark all the contact edges on the hull, cover with mylar tape, apply thickened slow epoxy and then lower the piece back in. When the epoxy cured we would take the piece back to the shop and finish the veneer and trim and paint and varnish and then bring it back and glue it in. The epoxy squeeze out was sanded off flush and made for a perfect fitting assembly. While grinding and fitting one day, there were 4 of us under the suspended piece grinding away . We had respiraters, goggles and earplugs as there was a LOT of dust and noise. I enede up with the bosch mini grinder which does not have a deadman style switch. Most of my mini grinders have dead man switches as I think they are safer. While repostioning myself with all of the noise and dust I didn't shut off the grinder and set my hand down on it with pressure. OW. I don't like grinders that don't shut off when the trigger is released.
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