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Confessions of a surface plate abuser
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- čas přidán 16. 10. 2020
- In this video we make a round cast iron sanding plate for detailing machined parts out of an off cut disc of cast iron. Contrary to popular shop practice using a precision surface plate for sanding parts on is detrimental to its accuracy. This simple to build plate will save your surface plate for what it was intended to be used for which is making precise measurements. Having the abrasive fixed to the plate is the secret of this technique.
12 inch wide 25 yard roll 220 grit silicon carbide paper for square plates can be sourced from abrasives-sout...
Check out Robins video on his Magic Surface Plate.
• THE MAGIC SANDING PLAT...
Just a Tip from Africa, we do not have the facilities to have tools delivered to our door, so as a surface plate alternative we use a good piece of plate glass, fairly thick, I have mine set in a recessed block of wood, so it is safer, and I keep in in the corner of my shop. I have cleaned some motorcycle clutch covers that leaked because it was ever so slightly warped, some high grit on the glass and rub it in a circular motion managed to bring the mating surfaces in the same plane, and hey presto, the cover can be put back on and no oil leaks.
Replace or turn the glass when you suspect low spots are developing. I check it by using a straight edge and feeler gauges.
Obviously do not drop the work piece on the glass.
Glas or even better mirrors. If a mirror is not very flat the reflection gets warped
You must have some beautiful night skies so if you happen to have a couple more thick glass blanks, about the size of an 33⅓ LP record you're on your way to a nice telescope....by weight at least. That size works great and gets your arms in shape for serious sanding. Just a thought...
I forgot to mention the search parameters: "John Dobson making your own reflector telescope". He's the solo version of a reflector telescope collective knowledge database. A natural guide. Cheers.
A good quality glass plate 1/2” or thicker has been a way to do this for a pretty long time. I use one myself.
I mean I don't know how expensive your glass is but a grade b surface plate like 24 x 24 is only 100-200 us dollars.and that's for large parts you can pickup a used starrett toolmakers flat out of class A Pink granite that is 8"x12" or 12"x16" for sometimes like 50-150 bucks.
What on your name ? 🤣@@BedroomMachinist
When I worked in the grind department at a company in Bad Axe, Michigan, we had one of these in each work area. They are very handy for cleaning up parts after they return from heat treat. We would rub the parts before measuring them on the plate and they thus saved wear on the plate (from the grit and residue which got stuck to the parts during heat treat, and which would have otherwise been rubbed on the plate and machine chuck) and made the parts stick much better to the chuck during the first cleanup. You could also easily see the locations of any burrs (and remove them) as well as the contact pattern which gave an indication of how the parts had warped in heat treat. They also put one at each work station in the mill department, where they could use them to knock off unseen burrs very rapidly. All of them were similar to yours, and used a full sized disk grinder pad, but had a 3/8" thick steel base which was Blanchard ground on both sides. They were heavy enough not to shift during vigorous scrubbing and yet light enough to pick up and move. At a cost of less than $300 in material, tooling, and time, I estimate that these would be cost justified in under a 40 hour work week for one person in a serious shop doing short production cnc machining and grind work. These were one of the most practical productivity-boosting hand tools in that shop.
I love watching these kinds of projects... No blue print needed, just dig in and get it done... I'm learning a TON from seeing you and other machinists work. Thanks for bringing us along.
When a surface plate wears a hollow it can easily be filled up again with some sharpie! :D
Or Bondo. **ducks and runs**
@@railgap 🔫
Robin and Tom, saving the world one surface plate at a time!
"...and if we can't, we put a groove in the middle." Classic. 🤣🤣🤣
Actually, lots of wooden chopping boards for kitchen use have a nice big groove round the middle, to act as a grip for lifting. So a large groove might save the work of drilling and tapping, and fitting those feet. :-)
@@paulwomack5866
⁷7
K7 I 09pl .
“Hi, I’m Tom.”
“Hi Tom!”
“I’m a surface plate abuser. I’ve been clean for 2 days.”
(Applause)
Step 8. Made a list of all persons we had harmed, and became willing to make amends to them all.
Step 9. Made direct amends to such people wherever possible, except when to do so would injure them or others
I think that means just buying more toys from Mr Starrett, right? A direct confession might cause emotional injury.
oh my god,,,, AA alone kept me from ever wanting to drive when i drink,,,, i hated that whole cult
Yeah, I have too confess too. I've done the same.
I'm a maintenance machinest in a plastics factory.
A couple months back I came into the shop, and the night shift mechanic had been working on some feed chains for a thermoforming machine and had used our 24x36 B Grade surface plate to set the chain on to swage the pins back into about 6 links. Needless to say, there are little pairs of chips that perfectly match #60 chain all over the plate.
I lost my mind, chewed his ass for a while and post a sign on the plate stating
"THIS IS NOT AN ANVIL
KEEP YOUR GODDAMN HAMMERS
AWAY FROM HERE"
The sad part is we have two 4'x8'x 3/4" steel work tables one only 4 ft from where he did this.
AAAAAAAAA!HHH!A!HG!HAHA!!!AAGAA!!!
Sounds like my coworker, and actually, a lot of people in general. I swear they look for the nearest thing to get a job accomplished, whether it be my tools, table etc. rather than doing things properly. Drives me up the wall.
I use filing cabinets as toolboxes, they're free :D, so I can't lock my stuff up. Ended up leaving different large notes in sharpie in all the drawers along the lines of, "Stay the fuck out of my tools and destroy your own garbage." My dad told me, "I don't use your shit, because I don't want you using mine." It'd be one thing if people were respectful, but in their eyes, a micrometer is just as good a c-clamp as a wrench is a hammer.
@@KISSMYACE3203 buy yourself some hasp and staples and padlocks and lock your filing cabinets that way when you are off shift lol. I certainly would or take the vulnerable tools like mics and such home every night lol
millwrights gonna millwright
And people wonder why there is a cage in the middle of a shop.
@@spehropefhany for putting the apprentice in after the 20th stupid question of the day? :)
Interesting to see rotary grinding. What did surprise me is that you didn't bother to bore the center hole when on the lathe to bring it truly concentric. Useful for other operations.
Hi Tom. A thought. After removing the material from one side (where the flat is), I’d flip it over, then make a very light pass with that X-acto blade to form a crease, then fold the sticky part of the abrasive disk over the other flat and trim the bottom. Now you can sand either one or both surfaces of a part that has an internal 90-degree angle (like an “L”-shaped piece.) 😎
22:13 That's the kind of thing I love doing. Taking a look at the cast-offs and offcuts and imagining what you can use them for is more fun than doing that with a solid piece. There's just a hint of a challenge to it, but no real pressure other than the desire to not waste.
Oxtools: "That is as close as we will ever get"
Abom: "Lets spend another 30 minutes centering this piece up so its dead on with no runout"
AvE: "It runs about 2thou off.....Good enough for the girls I go out with."
The Machinist world in 3 different takes.
Pakistani truck channel: "ਹਥੌੜਾ ਚਪਟਾ ਹੈ"
What? No love for dear Old Tony? For shame.
@@whatelseison8970 ToT: “that worked out closer than I expected.”
Yeah, we could have done without that last one.
When you were turning the OD, and counting down to the chuck jaws, I had visions of Captain Ramius, counting to the turn in the caves.
I really like the 4 jaw adjustment bolt setup for keeping the part parallel. I'm so envious of your wide variety of equipment and setup gadgets. I am living vicariously through your CZcams videos thanks
I do emergency machine repair. When a plant full of workers are standing around waiting on me to get a bottleneck fixed, all tools are sacrificial. I am not proud of that. I'm proud of the reputation, respect and compensation I receive.
Was anyone else going crazy as he stuck the sand paper down that there was a giant speck of dust that had settled on the plate and is now a class A scratchmaker?
The gloves being worn while at the bandsaw made everyone at OSHA quit
just gotta buy gloves that tear more readibly than a human finger joint
You yanks seem to have every tool for every occasion. Here in the UK in my shop I dont have the room. When I was an apprentice, I would have scraped this to blue. Now that was skill!
the best i have found on my cheap dedicated sanding reference plate is using 3m microfinishing film (or any mylar based sandpaper), wash the plate well, then put the paper down on the wet plate and squeege out the water from under the paper with a plastic card type squeege (very important) the paper is suctioned to the plate by surface tension, and not only does this keep the paper from moving and causing more wear on the plate, it keeps it quite flat to the plate so you dont have the leading edge of your part hit the paper wave and create a convex surface. work the part wet on the paper (not too much water or you will float the paper) the mylar based stuff dosent curl up like paper based sandpaper so you can re use it untill its dull. the 3m stuff is much more precision graded than regular sandpaper, and you can get it from 30 micron down to .1 micron.
I like how Tom used the correct form of "jury rig." A lot of people say jerry rig, perhaps mixing jury rig and jerry built. The two terms have nearly opposite meanings. Good on you, Tom!
The first step is admitting you have a problem. Good on you for building a tool to help.
You should make a custom "Mr. Bozo" shop magnet that starts out completely bald and grows hair with steel chips.
That’s just evil! 🤣
When you peeled the backing off the paper,
and then raised it up, it appeared to me that
something had fallen off of the paper and
was on the disc when you stuck the paper down.
Boy, Tom, it’s good to see some old fashioned lathe work on your show again.
YES!!!!!!!
never get tired of chips flying sawdust production. or filings. call me crazy. for now, I live via youtube machinist I don't have a problem watching each and every operation from start to finish. i like every detail so that I can know for sure how the job is done.
Really enjoyed this video Tom. I will probably never make this surface plate, but the little tips and tricks you through in almost as an aside are extremely helpful to me. Thank you
I will have to call you out on not cleaning off the plate again before putting the disc on, Fresh abrasives are notorious for leaving behind particles, especially laying down as it was.
Other than that, great video as always, you're like the mentor I've never met.
Nice project and good advice Tom, however, early on, that off-center hole drives me nuts! LOL. Great video. Well played.
I thought I was the only one. It makes your machinist senses tingle, and not in a good way!!! HAHAHAAAA
Was expecting him to machine it at least some
#same
Tom spreading your knowledge to all of us is really greatly appreciated more than you know thank you very much
While building my diy surface grinder I have already 150+ hours on it but I'm always watching your videos beside so it will take ages to finish the project 😂😂😂 I love your videos you are one of the best metal youtubers 👍👍🤪 With Rob, Adam,Toni,Joe and Stefan you're the creme de la creme 👍👍👍👏👏👏
Aloha Tom, I'm starting to worry about ME, I have a project set up in the mill that I left last night and here I set on a Saturday morning watching YOU work???? I do enjoy you talking through your thought process as I most always pickup on a tidbit of information here and there. Mahalo for your time and keep them coming.
McMaster-Carr is so awesome. They offer free CAD models that I use at my job all the time to plan assemblies. Great company.
Tom I like your idea with the Walmart bamboo drawer organizer...got one in my kitchen just like..!
Good video...as always..!
When applying the paper, I would align the half that has the backing on it so it will slide and then stick it from the center outward.
I do the exact same thing with my little 4x6 saw when cutting at an angle, pushing on the side of the blade until it catches.
I’m not a pro so wasn’t sure if that was a pretty sketchy thing to do, but I feel a lot better seeing a pro like you do the same thing.
At 5 minutes: putting the needle at 3 o'clock gets its movement inline with reality. Just a little something to help anyone wrapping their head around the variables.
That’s a tip!
Great video! Always a joy to watch!
Guys out there don’t get to caught up on the size of the plate, they make all kinds of diameter sanding paper to fit what ever you find for a disc.
You could make some magnetic feet that would be just a disk magnet with a steel post and self adhesive rubber pad. That would allow you to put a different grit of paper on the other side of the disk and just flip the feet to the other side when necessary.
Thanks for a really wonderful tutorial; this is how to make educational videos. Seeing you work on the lathe took me back to the 16 year old me, mid last century.
Thanks for putting that blast shield up, I didn't have my eye protection at hand when I clicked on your vid!
I trully hope none of my metrology student EVER treat a surface plate that way!! I wonder if I should report this video to the admins !!! Sand paper on a surface plate!!! there is a special place for people like you in the underworld :)
Really cool. I have some surface ground 1inch plates, in 2 sizes in length. I use them for the same application. When they become compromised I regrind them and good to go. Also they serve as a good reference surface for flatness . good job tom!!!!
Nice project.
On compressed air on machines. During my apprenticeship as a tool and die maker back in the 70‘s one thing we got hammered into our heads. Never ever use compressed air to clean precision machinery. During the year I worked in the mold shop we had the same rule.
Hey, i grind aluminium with grain alcohol (spiritus), makes the job much easier and the paper is not smearing up. You can also create a rotating plate, also much easier to grind with. :P Greetings from germany.
Ah yes, the old spiritus makes all sorts of jobs much easier. Just don't let the boss find out. 😉
Turned out great, nice project....I've been using a pastry makers marble rolling plate with the same 12" sanding disks. It's surprisingly flat and water proof for wet sanding. Enjoyed...thanks Tom !
I've got an old granite chessboard that I've long since lost the pieces for. The back of that is pretty flat, good enough for chisels anyway
Always informative and interesting. Never stop Tom. It was great seeing you at the Bash.
A little piece of tape can make removing an adhesive backing much easier. Enjoyed watching your work, thank you.
Nice video! A lot of woodchucks use sandpaper on glass as a flat surface for sharpening. You need a fairly thick piece of glass and many folks say you need "float glass" which is produced by flowing molten glass over a molten tin bath. I have used regular window pane glass and I think it is OK, but not surface plate accurate. Woodchuck stores also sell granite surface plates to use as sharpening platens with sandpaper. MDF from the big box hardware store is also remarkably flat and works OK, but does degrade over time.
Thanks Tom...I really liked this video. The straight edges on the plate are money! I'm gonna head off to my local machine shop to see if they can 'doit toit' for me. I think it will be great for for my little hobby wood shop.sharpening...and save my granite surface plate. I guess a thick slab of float glass could work also if I was gonna only sharpen wood cutting tools...but I think the steel plate has more usefulness overall..
Ahh sipping your coffee on a sunday morning while watching a new ox tools video is just great. Thanks for the great video Tom!
Lol
I knew where you were going with this before you said it.
Now I'll watch the rest of the video.
Great job! As a suggestion, I would have J.B. Welded a slightly undersize pin either before turning or roto-grinding. This would help prevent snagging on smaller parts or parts with sharp corners.
Learn something new every time I watch your videos. @ 8:00 I didn't know avocado pits were magnetic
Honestly, I was expecting a pressfit pin for the center of that plate before finishing.
Or NOT centre of the plate! Lol
Yes!
God at least a bodgy plug weld before it was all ground back to dimension!
Or, to piss off as many machinists as possible, but be fine for almost every other use.... go buy a 8 or 12 inch granite flooring tile from the local big box store.
Be careful though - they are thin enough to bend and take on the shape of the underlying surface. A better choice is to find a small custom kitchen countertop supplier. Their workshop probably has off-cuts piled up in the yard awaiting disposal, most of which have effectively zero value in their market. You'll likely find a suitable sized piece of 1-1.5" thick granite with better stiffness and flatness than the floor tile. Another potential source is countertop rip-outs on Craigslist. Be aware that countertops aren't precision-ground and the edges of abutting slabs are sometimes polished in-situ to reduce lippage, so they aren't suitable for precision measurements. With a little effort you should be able to find something usable for sanding though, and if you got three pieces and lapped them together with diamond paste you could end up with something better than anything not sold as a precision surface plate. At some point though you need to remember that a Shars Grade B 9"x12"x2" surface plate is only $30, and a 12"x18"x3" only $50.
How about a manhole cover?
thick glass plate
@@thebad300 Yes. 0.5" plate glass is a good substitute.
A tile like that won't be flat enough, for precision work. a machined plate like this really is the ideal thing.
Pretty nice plate, I live where cast Iron likes to turn into Iron Oxide in 3 nano seconds. Shars $30 looks like a good idea.
Cast iron? Surface grinder? Meh (joking) :D There was a banktrupcy sale on granite bases for big sunshades (you know - for the big umbrella) in a local furniture warehouse. About 10 bucks (original price 55 bucks) for 1 piece! Bought three, around 2,5 inches thick, cut out circles out of them with a cheapo diamond wheel in an angle grinder (Dust YUCK) and grinded them to nice circular shape with a standard stone wheel, lapped them together with 3 plate method with using silicon carbide, aluminium oxidem finished with ebay diamond dust (40 micron down to last 12 micron) and voilla! 3 precision plates for sandpaper OR lapping other very hard stuff (hardened steel and harder). Observations: It didn't took long to get it sort of planar (they were polished on one side and surprisingly planar from the get go.. made in germany), slicon carbide breaks down very very fast (it's interesting to see how al.oxide breaks down far slower), water helped up to a point and then plates started sticking HARD (shape match sign)!, took me 4 days (about 1,5 hours a day), had to make a concave/convex measuring tool (big thick aluminium square rod, 3x holes, 1 screw, 2x Abec 7 ball bearings, superglue and 1um dial indicator) so I know where I am at in comparison to a certified AAA granite plate. It was fun and the results are superb!
Fantastic story. I'm not sure if I have the energy to do something like that myself.
@@ddegn I think the worst part was the granite dust during cutting and grinding to shape. Luckilly I had all the abrasives needed (bought for cheap long time ago from a glass artwork shop.. except the diamond from ebay of course)
Would have been a great YouTuve video!
Nice new tool for the shop, good to see you again,,
Tom, this turned out great! My inner voice is saying 3 points of contact for the feet but I wonder if that might cause tipping at the non-supported edges. Anyway, thanks for sharing!
In the optics trade we use cast iron laps all the time. They work great with loose abrasive, just paint as many surfaces as you can and keep the rest oiled.
What i dont understand is why you machine shop chaps dont get a simple lapping spindle. Your lap will wear much more evenly if it is spinning and you can use the position of the workpiece to adjust from convex to concave.
The only downside here is, that hunk of cast would be near $300 or more, up here in Ontario in my neck of the woods. I tried to get my metal supplier to bring in a 2” x 2” x 18” chunk of cast so I could make a straight edge and it was going to be $130...
300? Oh god.. it would be cheaper to buy old cast iron brake discs (every scrap yard has tons of them), melt them in a 200 dollar furnace (old tank, ceramic cotton, firebricks, fireproof mortar, propane + diy venturi burner) and pour into a very crude sand mould (open top.. just a bunch of wet sand with a circular imprint)
A clever guy might take a look at some cast iron free weights at the local sporting goods store.....
Cheers,
Tom
@@oxtoolco - I've done that. What a horrible experience!
I made a back plate for a Pratt Burnard collet chuck from a dumbbell. Full of voids, weird chunks that would break the brazed tool bit, it smelled weird?! I'll be honest, I was warned about using free weights as a source of cast iron, but I did it anyways. I've heard them once described as compressed chinese street grime.... I've also heard chinese inserts described the same way. Lol.
@@shawnhuk You have discovered a new alloy! "CCSG" iron, Dumb bell grade. Got a good laugh out of that one.
Cheers,
Tom
If you can find some old York plates, they used to machine the backs of these plates to achieve closer weight tolerances. The set that I had (and sold to fit my lathe and mill in the garages) looked beautiful. There were no voids or irregularities in the machined back side.
I am curious what goes on in the minds of people who give this a thumbs down 😳. You make great videos! 👍👍
Nobody disliked the video, people just dislike theyre not as good or don't have the facilities. But they like the video ;-)
Heyyyy!!!
I'm new to your channel. Nice work and I enjoyed the video. Down to earth, little humor and right to the point!!!
I'll be here for awhile!!💪🏻👍🏻
The irregular sanding pattern on the sand paper shows that it is less flat than the base plate by orders of magnitude. You need to use diamond paste instead.
An incredible amount of work to make something you could have just purchased.
Your demonstrate good quality control in your shop-good work!
Before Tom even finished I knew he was going to mention Robin!
if you make yourself some little copper covers that wrap around the chuck jaws (ie just use a longer strip of copper and bend it around the jaw) you can slip them over the jaws and not have to worry about having copper shims slip out when you back the jaws off too much while dialing in the part
I absolutely love that wheel centering tool!
Never knew about this. We always used a parallel bit of C250 Aluminium and double side sticky tape some emry tape to the back of it
You can clean the chuck by sucking with Your shop vac from the back of the lathe and then using a bottle brush to clean the jaw threads. Cleans the jaws and their threads really well unless You let go the bottle brush into the shop vac.
Some granite floor tiles at big box stores are extremely flat- I use one of those for most sanding if I don’t need greater precision
I still use a surface plate for larger items, but for things less than about 10" I use a piece of 12" square granite tile. It's actually really flat.
Yup a piece of Blanchard ground steel plate or a cast iron plate like an old table saw is a good thing fot using abrasives on.
i used to cut a lot of brake drums and rotors on various drum and rotor lathes.. i always tried to have some inch and a half disposable natural bristle wooden handle brushes next to the lathe.. i would rest the side of the bristles on the cutting tip.. so it deflected the chips downward.. nylon bristles just melted as did plastic handles sometimes. it does block the view.. but i would rather not have chips everywhere .
Hi Tom,
A job well done... Thank you for sharing...
Take care
Paul,,
Such a NICE bandsaw!
Cool video this is the 1st video of yours I’ve seen I like your work and personality you seem very easy to get along with so I’ll be checking out more of your videos.
Very well done as usual. Now I know what to do with all those 12" cast iron cutoffs that I don't have.
Find a place that does stone/granite/marble countertops, they cut out a piece for sink to fit into.
Usually pretty close to flat and less than $20.00 as an off-cut.
Pretty sure it would cost way more than that just to ship a large chunk of cast iron? (plus whatever it costs for a piece the size you had?)
Damm that's a smart idea.... Allso tombstone makers are worth a visit.
@@africanelectron751 .as long as it isn't recycled from the cemetery ;o)
A starter guide bearing project for your bandsaw. One that pops out the way...or a brush handle bearing...
You guy's crack me up! "I'll just use this scrap piece of 300mm x 32mm cast iron". Now, where will the average home machinist find a huge "scrap" piece of cast iron? I can't even lay my hands on smaller chunks of cast for projects without buying them for ridiculous prices off the usual suspects. I'm pretty resourceful but sometimes I think you guys live in your own crazy world where unobtanium falls from the sky along with the tools to work and measure it.
As ever, lovely work. Thank you Tom
That's minor Tom, I worked in an aluminum castings shop in the straightening department. We had two sections the small parts section worker on castings that for the most part could be easily held in one hand. They had six work stations each had a surface plate typically 24 x 36. And a beating plate the same size. The beating plate was two inch thick semi polished steel. I was promoted to the large castings side where each work station consisted of just a 48 x 72 surface plate which was used to base qc and straighten parts. Chips and pocks where the norm. If they got to bad we would fill them with epoxy. Needless to say it felt pretty sacrilegious to beat on the plates like we did but corporate didn't seem to care
Tom, I always marvel at your saw ! Cheers, Cliff
In my old Canberra sharehouse, my cohabitant had a big ol piece of stainless propping open the door with "That's Mr Doorstop to you" written on it
I really enjoyed this video Many thanks
Awesome video! I learned a boatload! Thank You!
nice touch with the flats. I got some sink drops from a granite counter top shop
Seriously, awesome video. Loved it!
You are very brave to tap a hole in that fashion.
Question from a non-machinist.
Wood workers and cabinet makers often have centralized vacuum systems with collection pipes at every machine. Why not so much with machinists? Seems like some sort of flexible vacuum nozzle rigged up next to the cutter would collect all the dust and chips where they're being formed instead of flying everywhere.
Thanks for the video and the tip about Shars.
I just ordered a 9X12 Grade A surface plate from them on your recommendation.
It was cheap enough but the shipping made my butt sore.
Lol!
I assume that you ordered the Grade A because the two ledges make it easier to handle. It's a shame that Shars discontinued their red granite plates - the 9x12x1 would be great in this application - relatively light and very hard wearing.
very very good video..thanks for your time
You could use a crepe block to clean your abrasive. It helps clear between the grains and extends the life of the abrasive. Just a thought.
41:01 get yourself an eraser, the ones for pencil on paper, but a big one (usually have a print on it "for big mistakes"). They work like a charm for cleaning sandpaper / (diamond)grindingstones, produce way less smearing compared to those un-vulcanized latex-rubbersticks some woodworkers use for their beltsander and you don't spread so much dust in your workshop. (You still need the brush for the finer eraser crumbs, but they are significantly larger and won't fly a fraction of the distance)
2:53 I had a real "oh snap he's gonna do it!" Moment. Then it was just a tape measure
ant kitchen countertop shop will have tons(literally ) of sink cutouts and other scrap to use for a lapping base
High School Machine Shop Teacher would of Slapped me back into Third grade if he saw me operating the Lathe with Gloves On ☺️💥🥊
Nitrile gloves rip instantly, no real danger of them catching.
@@ImmaculateLamp Perhaps, but barrier cream on your hands has zero risk.
I've heard people make that argument before, but I'm not aware of any safety statistics providing evidence one way or another.
ive been told put saran wrap or package cling wrap on the surface plate when sanding