Bulk cutting of 2" hook and loop sanding discs?

[rsser]

A while back there were posts on this and from memory TTIT was using a modded hole saw.

Teeth ground off and an edge put on the hole saw?

I have to get serious about it as I'm sick of punching out one at time with a sharpened muffler pipe.

There's two choices.

One is a cheapy set of hole saws to hand, spring (saw) steel but with a gap; all fit into a single top plate via lugs and recesses. Can't see that grinding the teeth off the relevant size will be all that easy and the gap might prove troublesome ... ?

Other choice now to hand is from the local tool supplies place that had individual bimetal hole saws on sale, plus all of 20 bucks for the chuck & drill. So that would involve grinding off the HSS teeth and putting an edge on the 'drum'. Also doesn't sound like fun.

That second choice is prob the best way to go, and I'd welcome advice about doing the mod.

[Ozkaban]

Dunno Ern, but what would happen with the muffler pipe and say 5 layers of sandpaper? Would it be a disaster, or do you reckon it would work ok?

2" holesaw shouldn't be that big a deal. The 3" ones are the buggers to get hold of.

Cheers,
Dave

[rsser]

Thanks for the thought Dave.

Getting one clean cut pounding on the sharpened pipe is rare, and the paw complains too much anyway. Time for horsepower rather than pawpower.

[A Duke]

How about making a press along the lines of the can crushers that plans appear for every now and then. Just put your sharpened pipe in and an end grain anvil underneath the sheet and give it a squeeze.
Just a thought.
Regards.

[Scott]

Ern, have you thought about using a hollow punch? I know 50mm ones are available but can't for the life of me locate them in Melbourne. My old man has one and makes disks of carboard out of them. Can imagine they'd go through sandpaper ok.

Other than that, If I were looking for a cheap fix, I'd use some scrap ply, add 50mm holes and sandwhich the sandpaper between and drill through the holes.


Hope those couple of ideas help.

[Woodwould]

I have a hand press that cuts out discs of fabric. I don't know whether exhaust pipe would withstand the pressures, but a decent bit of high carbon pipe or tube with a properly dressed edge should be fit to punch out at least five at a time even in a small hand press.

[John T]

HI RSSER
I made my own sandpaper cutter 50mm exhaust pipe expanded to 53mm and welded 50mmx 25mm plug in top, I held it in scroll chuck and sharpend with a flat file have cut 100s without having to sharpen it i use a block of redgum end grain,I had them on the forum about 2 years a go.
regards john.

[TTIT]

I think it was Hughie using the hole-saws Ern. I'm still using an old pair of scissors so I'll watch this thread to see if there are any ground breaking ideas floating around.

[issatree]

Hi All,
My thoughts were to get hold of a small 2 Tonne Jack, put into a base of some kind . You would have to put a foot on the Muffler Pipe, & you don't have to turn the jack upside down. Like was said, to use a piece of Red Gum or whatever, & it should do up to 8 sheets, surly.
Made something similar many years ago, & put 2 springs on it to lift the Jack back to the start, when finished.
Having a bit of trouble here explaining myself, but I hope you get the drift.

[hughie]

Ern, Hole saws are the way to go as most are made from carbon steel with a HSS edge added. Always go for the welded ones as they have a heavy back end ideal for thumping with a hammer


http://www.woodworkforums.com/f8/hole-punch-sanding-discs-66063/


Hole punches will set you back a few bob on the bigger sizes. Thats why I never bothered to use them. Exhaust pipe is way too soft and will deform rapidly with pressure, thats is design so it can be bent. :U No doubt you've found that out already.

[dr4g0nfly]

I'm the same as TTiT and using an old pair of scissors but a Registered Professional Woodturner I know uses the hole-saw method to great effect.

As you've noted, he uses a Bi-Metal saw with the teeth ground off and sharpened edges.

I can remember that he did not use a 50mm (2") but rather one slightly larger (52mm or 53mm) as when you grind the edge you are creating the inner diameter as the sharp edge, whereas the drilled hole will be measured to the outside edge.

I've converted a couple of them for ball turning, but instead of buying them I blagged them off a plumber friend who had worn them out and were otherwise destined for the bin.

[rsser]

Thanks for the links and tips folks.

Dragonfly, yep, the good 'un is 54mm OD, c. 50mm ID.

[bdar]

Hi Ern,

Here is a link to the sandpaper man for wad punches for 50mm and 75mm for cutting hook and loop. It would save a lot of mucking around in making them. Hope it helps. Wad Punches | The Sandpaper Man (http://www.thesandpaperman.com.au/Wad-Punches/)

Cheers
Darren

[rsser]

Thanks Darren. They look the goods.

For the moment I'll pursue the hole saw idea having bought the bits.

[Jim Carroll]

If you want to get them closer to home we have them here (http://cws.au.com/shop/category/-wad-punches-titanium-coated) Ern

Just noticed you signature Ern, some nice photos of work there.

[NeilS]

I picked up on Hughie's hole saw idea and it works very well. As suggested by him grind off the teeth with an angle grinder while rotating the hole saw in the drill press or lathe to ensure the entire cutting edge will be square to the drill press table.

The bevel for the cutting edge should be on the outside.

If you don't already have a slit or hole of some sort in the saw backing plate.. add one so the cut disks can be pushed out from the top. They get packed in there when cutting multiple disks at a time.

As with manual punching, cut from the backing side of sheet. That helps to part some of the abrasive particles before the cutting edge runs in contact with it and helps to prolong the time between sharpening.

The tricky bit is holding the multiple sheets in place while cutting, I haven't found an ideal solution for that yet.

[Paul39]

I would try cutting a sheet without grinding the teeth off. A soft edge on the sandpaper would not hurt.

One could make a hinged book from plywood with a predrilled hole in the top. Put however many sheets between the plywood , clamp and attach hinges.

Put the sandwich on the drill press and run down the spindle to fit the hole saw in the hole, clamp the open side and cut.

[robo hippy]

In the leather industry, there are 'clicker' dies. Hard steel, made to size, usually with some neoprene inside, and plywood backing. They are made for a table top hydraulic punch press. You may be able to find a leather shop that will let you use their press. I have 1/4 inch thick pipe sections, about 1 inch high. Use a 1/2 inch thick piece of plastic, set up 5 or so layers of abrasives, put a piece of wood on the metal, and use a 6 to 10 pound sledge hammer. No problem going through 5 layers, though you don't always strike level, so you may have to hit twice. The pipe is reamed out slightly on the inside, and a double bevel on the cutting edge (single bevel will tend to crimp over). Important to have punch board right over a table leg, rather than in the middle of the table. I don't see why it wouldn't work with a hole saw, but you would still want the wood over the metal, and you will have to remove the discs from the saw. I had tried arbor presses, but they don't hold up unless you have a really heavy one (5 ton or more), and the sledge is easier.

robo hippy

[hughie]

[. You may be able to find a leather shop that will let you use their press.


Pretty hard here with the OHS laws especially in Victoria where Ern is located. They have some of the toughest in the country.
But a good idea and ideal if you could swing it.

[hughie]

.




The tricky bit is holding the multiple sheets in place while cutting, I haven't found an ideal solution for that yet


I have often wondered if a slow rotation of the hole saw rather than pounding it would not be better for multiple layers. I have done this with other materials but never with sandpaper and ideally have the abrasive side down when doing so.

[rsser]

Paul, good idea :2tsup:

For a trial I used a bit of Perspex on top ... gives the advantage that you can see to position the pack.

First run of 5 sheets, it was clamped on one side, hand held on the other. It did some walking but there was a good result. 2nd run: clamped both sides but the finer discs at the bottom got crumpled a bit on exit.

The Perspex is too thin; about 3mm. Double that or more would be better.

So the hole saw minus teeth and with the outside bevel honed with a diamond credit card is sharp enough to go into the melamine scrap on this table :rolleyes:

The saw was $9 on sale at Total Tools (Preston, Melb.).

Added: the drill press was running at 250 rpm.

[rsser]

Update: this is going gang-busters :D

Takes about a minute to position, clamp, cut and extract. Stacks of 5.

Have found that sandwiching fine sheets between coarse, heavier-backed sheets, eliminates any crumpling.

Producing years' worth of discs, from #80 to #1200.

[Ozkaban]

Update: this is going gang-busters :D

Takes about a minute to position, clamp, cut and extract. Stacks of 5.

Have found that sandwiching fine sheets between coarse, heavier-backed sheets, eliminates any crumpling.

Producing years' worth of discs, from #80 to #1200.

sweet:2tsup: nice progress:cool:

[rsser]

Dave, I did give your suggestion a try out of interest.

Starting out with the muffler punch (pictured) it was clear that the outside had splayed. I was maintaining the bevel on the inside. So correcting the splay freehand on the grinder, I had at a stack of 5 sheets with MDF underneath.

The result was again not a complete cut, but the big advance was that it was only one thumping session for five scissor sessions :) So thanks.

The pipe must be stainless; the folds at the top are a by-product of many thumping sessions :doh:

...

If a beginner wanted to get into this game and had good hands, I'd recommend the punches Jim or the Sandpaperman stocks.

[Ozkaban]

Cool to hear :cool:

The folds on the top look awesome :D

Cheers,
Dave

[rsser]

Nice bit of incidental art ;-}

So, after 14 stacks of 5 sheets each, the edge needs honing.

[robo hippy]

If you stack abrasive to loop/fuzzy side, very little migration. With the plastic punch board, they will cut all the way through. Having a wood pounding board over the metal prevents crimping. Cutter needs to be no more than 2 inches high. You could do a club purchase of a lot of abrasive, if you can get them to agree on which abrasive, and have a punching party. I used to pay my daughter 1 penny per disc to mark the abrasive grit on each one, as most of the abrasives don't have grits marked so that it will show up on every disc. They really should color code the grits.

robo hippy