Gluing MDF disks to metal rod

[dave harris]

Greetings

In building a drum sander i have come across an interesting question. I need to glue mdf disks to a 1" steel rod and was wondering if yellow glue being water base would swell the mdf disks enough to adhere to the metal rod. I read this opinion in another forum. or would construction adhesive for wood and metal be better option?

Opinions appreciated

Thanks

Dave

[Jamie Buxton]

Yellow glue doesn't bond to metal. Epoxy would be a better choice. It bonds well to both metal and wood. Degrease the metal before you apply adhesive.

[Peter Aeschliman]

x2 on 2 part epoxy. Water based glues will definitely swell up the MDF.

I recommend roughing up the metal with some 120 grit sandpaper before degreasing as well. Even then, I'm not positive the "end grain" of the mdf will be a good gluing surface, but epoxy is definitely your best bet. Not trying to be critical at all, but if I were doing this I would probably go with something like poplar instead. In that case, only some of the disks' gluing surfaces would be end grain, so you're more likely to get a solid bond.

[Jay Maiers]

I'm not a glue expert, but I don't think I'd rely on that long term. Any chance you can use a keyed or splined shaft? Perhaps drill a hole through the rod and use a pin that fits into a slot in the end disc?


ETA: I'm assuming you're talking about the sanding drum here and not some other part of the machine...

[Bruce Wrenn]

Use a slow set (90 minute) epoxy. This way you can get all the disks on from one batch of epoxy

[Lee Schierer]

I'm not a glue expert, but I don't think I'd rely on that long term. Any chance you can use a keyed or splined shaft? Perhaps drill a hole through the rod and use a pin that fits into a slot in the end disc?


ETA: I'm assuming you're talking about the sanding drum here and not some other part of the machine...

Or get a local machine shop to knurl the part that will be inside your blocks and use epoxy for you adhesive.

[john bateman]

I would glue the discs together then use a bushing similar to this picture to hold the discs to the rod.
218811

[John Aperahama]

Epoxy works fine with no added strategies. Been there done that (actually used particle board)

[ian maybury]

I've had great results on jobs like that with a single part moisture curing polyurethane structural bonder/sealer of the sort used by automotive repair guys for windscreen, metal panel and metal to plastic bonding. Texflex PU is one that's locally available here http://www.cfsnet.co.uk/acatalog/_NEW__Texflex_PU.html, but it's pretty generic - Teroson, 3M and the like all do equivalent products. About €6 for a 300ml cartridge.

I used to use epoxy a lot, but find the polyurethane better all round - more than strong enough, cheaper, no mixing, handles beautifully, good gap filling, different colours (at least grey, black and white), and cures to a resilient, tack free and gloss surfaced solid. Gets a really ferocious bite on lots of difficult surfaces, and the slight flexibility tolerates big differences in expansion.

It's excellent for jobs like bonding pressed metal ducting fittings into e.g. a ply dust box as on a router table. It also bonds metal duct fittings into PVC waste pipe, or metal to metal fittings and the like in a way that seems very unlikely to ever move.

The only real downside I've found is that a cartridge once opened starts to thicken after a few weeks, although a bit of creativity with silica gel or something would probably get around that.

ian

[Jerome Hanby]

You can glue all the disks together to make a cylinder, cut a notch across the hole on one of the outside disks, drill a hole through your shaft near one end, insert a pin in that hole, then slide the cylinder onto the rod and the notch over that pin. You can use a big washer over the other end and rig some similar type pin to hold it in place. That arrangement would also allow you to replace the cylinder without scrapping the shaft.

[Myk Rian]

I would use Gorilla glue.

[Phil Thien]

I would glue the discs together then use a bushing similar to this picture to hold the discs to the rod.
218811

This is the best answer, IMHO.

[Rich Engelhardt]

You can glue all the disks together to make a cylinder, cut a notch across the hole on one of the outside disks, drill a hole through your shaft near one end, insert a pin in that hole, then slide the cylinder onto the rod and the notch over that pin. You can use a big washer over the other end and rig some similar type pin to hold it in placeIIRC, that's similar to how they did in in one of the magazines I read on building a shop made drum sander that goes on a table saw.
The disks were glued together and one end slotted to accept a pin.

Why MDF though?
I'd think Baltic Birch disks would be a lot tougher & hold up better.

[Jerome Hanby]

I'm using MDF for a few reasons.

1. I've got a lot of MDF scraps and this is a good use for them
2. It's heavy. A little inertia once it gets up to speed seems like it would be a good thing.
3. It's solid. I've never seen any plywood that was "perfect" on the edges. That could very well be my local suppliers, I'm not sure their Baltic birch is the same thing everyone else talks about.

I'm sure how much tougher the drum material would need to be. I'm planning on lathering mine with shellac until it quits absorbing. iIthink the end product will be plenty tough enough. What I'm still thinking through is a method to make the drums easy to interchange. My thought is that I'd be more likely to swap between grits if I could just swap drums. Rewinding with a different grit is enough trouble that I'd be less likely to ever do it.


IIRC, that's similar to how they did in in one of the magazines I read on building a shop made drum sander that goes on a table saw.
The disks were glued together and one end slotted to accept a pin.

Why MDF though?
I'd think Baltic Birch disks would be a lot tougher & hold up better.

[David Hostetler]

FWIW, I started making my drum out of 3/4 MDF, had the disks cut and all, set them aside to finish a project that I was time crunched on, came back to it and they were swollen up from moisture in the air. MDF does NOT like humid environments... Something I can't avoid in Coastal Texas...

So for me, the option has to be either solid, wood, or ply, and ply seems to be more stable when RH stays 70% + over half the year...

To attach the disks to the shaft, my plan is to use plenty of slow set 2 part epoxy. Do NOT use the 5 minute stuff, you don't have enough open time with that to be able to actually get things right...

I am a bit curious though. Why a 1" shaft? That seems awfully thick... I am planning on using 3/4" and from what I have seen I am going large diameter compared to many. Most I see use 5/8" smooth rod for the shaft...

[Larry Edgerton]

Jerome

Instead of the shellac, I would suggest hard surfacing the drum with the same epoxy you use for the shaft. I use West System with 207 hardener for all of the patterns that I make out of MDF so that the surface that the bearing runs on does not get distorted with use. It works amazingly well.

Larry

[Jerome Hanby]

Thanks for the recommendation. Do you just brush the epoxy on to the MDF surface? Does it lay out smooth or do you sand afterwards? Sounds likw a good product to acquire. I notice on my MDF templates it doesn't take long (like maybe once <lol>) for my guide bearings to start making a dent, does this stuff solve that problem? Duh, just reread your post, that was your point. Looked at teh west web site and looks like you can use a roller to apply the stuff...


Jerome

Instead of the shellac, I would suggest hard surfacing the drum with the same epoxy you use for the shaft. I use West System with 207 hardener for all of the patterns that I make out of MDF so that the surface that the bearing runs on does not get distorted with use. It works amazingly well.

Larry

[Derek Chalmers]

I would glue the discs together then use a bushing similar to this picture to hold the discs to the rod.
218811

Where would one be able to get some of these bushings? I am currently planning my own sander and think these would be a great problem solver

[Steve Rozmiarek]

Derek, McMaster Carr lists this conveyor belt pulley,

http://images1.mcmaster.com/Contents/gfx/large/5706k124p1l.png?ver=27762855

available in 2" to 8" diameter, by up to 38" long. $70-$280. Looks interesting to me if I understand what you guys are doing.

www.mcmaster.com/#conveyor-belt-pulleys/=luxkiy (http://www.mcmaster.com/#conveyor-belt-pulleys/=luxkiy)

a link to the bushings you asked about is: www.mcmaster.com/#flanged-linear-bushings/=luxo87 (http://www.mcmaster.com/#flanged-linear-bushings/=luxo87)

[John TenEyck]

I made mine with MDF and a 3/4" shaft. I glued the MDF disks onto the roughened steel shaft with extended time epoxy. After it cured I turned it on a metal lathe, between centers, and then spun it up to 2500 rpm. Steady, smooth, no vibration. I chose MDF because it is very consistent in density so I wouldn't have to worry about having to balance it. At that point I found a used drum sander and bought it, so my home built one never happened.

John

[Derek Chalmers]

[QUOTE=Steve Rozmiarek;2079081]Derek, McMaster Carr lists this conveyor belt pulley,

http://images1.mcmaster.com/Contents/gfx/large/5706k124p1l.png?ver=27762855

available in 2" to 8" diameter, by up to 38" long. $70-$280. Looks interesting to me if I understand what you guys are doing.

www.mcmaster.com/#conveyor-belt-pulleys/=luxkiy (http://www.mcmaster.com/#conveyor-belt-pulleys/=luxkiy)

a link to the bushings you asked about is: www.mcmaster.com/#flanged-linear-bushings/=luxo87 (http://www.mcmaster.com/#flanged-linear-bushings/=luxo87)[/QUOTE

thanks Steve. I did a bit of investigating and found some if the tapered bushings like the ones previously pictured
mat Motion Industries and the have an outlet near me. I may try and check stock tomorrow. We have something
similar at my work but the flange is
really small and most likely not large enough for a lag type fastener appreciate the
Heads up on the conveyor drums etc !

[Ellery Becnel]

Thanks for sharing John. My design is almost identical to yours. 7/8" shaft, MDF, between centers, epoxy, Dynamic balance, Drive flange, link belt, & a !/2 hp. motor. Just about ready to fabricate. All parts have arrived. I am looking forward to minimal sanding on my end grain chopping boards. I know it is overkill, but i just can't help it.

Ellery