Mini-Orbital Sander For Mold Making/ Fiberglass Work

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PostPosted: Tue Jan 31, 2023 9:55 pm
I'm hoping someone can share some experience on small orbital sanders. I'm not doing autobody work per se, but I thought autobody guys would have a lot of experience that would overlap with the work I am trying to do.

For a little background, I am trying to make production tooling (fiberglass molds) for producing a carbon fiber knee pad design I came up with. I'm doing this by machining the plug (a positive of the final mold) on my CNC router, then sealing, clear coating, and polishing. Then I make a mold negative off the plug. Then I need to polish any defects I missed, and from the negative make the master mold, which needs to be as perfect as possible!

The molds are ~18"x24", and there are a lot of contours. The only part that is flat is the flanges.

I'd love to find a quality orbital sander that is less than 3". (I see plenty of 3" options, but that is kind of big for what I need.) And it would have a complete range of abrasives, ranging from 400grit to 2000grit. Discs need to be flexible, and I need a good soft to medium interface pad to deal with the contours. Hook and loop would be great.

Does something like this exist? What would you recommend that isn't the Harbor Freight sander? (Sorry, personal prejudice...)

Right now my concern is making sure the abrasives are there before buying a sander. I've seen a few sanders that look great (and expensive), like the 3M mini-orbital sanders. But trying to navigate 3Ms catalogs breaks my head! I can't figure out if they have flexible hook and loop sanding discs in my desired range of grit, plus interface pads to fit their small roloc backing pads....that would fit the mini-orbital sander.

(BTW, I will be buying a 7.5hp compressor soon, so sander CFMs won't be a problem.)

Thanks
Darren

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PostPosted: Wed Feb 01, 2023 12:39 am
Darren,
Stop, take a deep cleansing breath.... go here.., http://www.supergrit.com ( If that link is not working just type it into your browser) Take some time and look through their online catalog. Next write down their phone number and see if you can talk to the owner, Arturo. See if he has some opinions on what type of machines his industrial customers are using. Honestly, these specialty small sanders end up being pretty pricey and they are almost ALL real air hogs. Dynabrade makes some crazy small orbital sanders going down to 1 and 1/4 inch diameter however they are in the $400 to $1000 price range and eat like 20 cfm. They need to be oiled daily and rebuilt every couple of years....
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PostPosted: Wed Feb 01, 2023 7:44 am
DarrelK wrote:Darren,
Stop, take a deep cleansing breath.... go here.., http://www.supergrit.com ( If that link is not working just type it into your browser) Take some time and look through their online catalog. Next write down their phone number and see if you can talk to the owner, Arturo. See if he has some opinions on what type of machines his industrial customers are using. Honestly, these specialty small sanders end up being pretty pricey and they are almost ALL real air hogs. Dynabrade makes some crazy small orbital sanders going down to 1 and 1/4 inch diameter however they are in the $400 to $1000 price range and eat like 20 cfm. They need to be oiled daily and rebuilt every couple of years....


Thanks. The website is happily easy to navigate, but they are missing the range of grits I am hoping to find. The small sanding disc section offers small disc sizes from 40-320. Nothing 400 or finer in the sub 3" size. But I want to start at 400.

They do have finer grits, but those are in 3".

I suppose I can always cut down larger discs or sheets, but it seems odd that nobody is making small discs in the grits I'm looking forl

And as I commented, don't worry about air. I will be buying a 7.5hp compressor rated at 28cfm @ 175psi (Castair). So I'm not worried about air consumption. I am getting the big compressor because I know the struggle!

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PostPosted: Wed Feb 01, 2023 9:21 am
If you don't see it on his web site that does not mean that he cannot source it for you. In the past he has sourced and recommended things that I did not think existed. Also, you can indeed make your own punches which are similar to veneer punches. You can use simple iron pipe and sharpen it down for cutting on one end and fill it about 1/2 full with lead or simply used a flattened pipe cap for a hitting surface. You can make it and do a heat treat on it to maintain it's sharp cutting end.
The reason you don't find the small stuff is because the woods/metals industry has no need for sanding processes which require small surface sanders. High production furniture manufacturing does little to no bare wood sanding at all.
Metal, wood, fiberglass, we work it all... www.furniturephysicians.com We can restore the irreplaceable!



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PostPosted: Thu Feb 02, 2023 7:31 am
Yep, if you can't find it make it. I've cut down hook and loop discs to fit my 3" sander, or the 2" pad I made, for finer grits that I can't find. Esp. for sanding thin stainless steel trim moldings.



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PostPosted: Thu Feb 02, 2023 8:05 am
chopolds wrote:Yep, if you can't find it make it. I've cut down hook and loop discs to fit my 3" sander, or the 2" pad I made, for finer grits that I can't find. Esp. for sanding thin stainless steel trim moldings.


Thanks. I sounds like custom cutting is the way to go. I guess it isn't bad--I can buy one type of paper for a 5 or 6" orbital (haven't decided which size to get), and cut down that paper for the small sander.

The mention of a made for purpose punch previously also makes it sound better that cutting each piece by hand.

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PostPosted: Thu Feb 02, 2023 10:57 am
So I am mostly in the wood industry and punches are a way of life for us. You could take black iron pipe and even weld a bunch of them together so you could make multiple discs at one time using a simple press. Even the craftspeople in third world countries make various punches for their wooden veneer puzzle and art marquetry pieces.....
Metal, wood, fiberglass, we work it all... www.furniturephysicians.com We can restore the irreplaceable!



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PostPosted: Thu Feb 02, 2023 6:54 pm
Are you vacuum infusing these parts? If you have a lot of contours then wouldn't shaped sanding blocks be better?



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PostPosted: Fri Feb 03, 2023 9:44 pm
myke wrote:Are you vacuum infusing these parts? If you have a lot of contours then wouldn't shaped sanding blocks be better?


Well... The shape of the parts is pretty simple (approx knee shaped...), and I'm currently using a wet-preg method and a silicone vacuum bag. I don't see a reason to complicate things with infusion.

The molds have a lot of contours because I am making multiple parts on a single mold, so the surface has to smoothly transition from one to the next.

If there was a repeating shape like a moulding, then a shaped block would be great. But for my molds I'd need a sanding block the shape of a french curve! Hand sanding really isn't terrible, but it's time consuming to work through the grits to "hopefully" end up without any scratches.

The sander is just to save some time on the easy parts. I'll still have to hand sand the detail stuff.

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PostPosted: Sun Feb 05, 2023 9:00 am
Ever thought about using something like flutter wheel sanders or something like a Mac Mop setup. Here is a Mac Mop....
https://www.klingspor.com/Product-Catal ... 3100531930
For industrial chair jobs we set up for one of those.... Mop is mounted to a large steel spindle direct drive off of a 1/2 hp electric motor. We also use air driven flutter wheel setups as well. With the Mac Mop you bring your part to the wheel. Flutter wheels are moved over the surface by hand....
Metal, wood, fiberglass, we work it all... www.furniturephysicians.com We can restore the irreplaceable!

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