Thread: Belt Sander

Is the graphite backing pad on the platen still there?

If this worn away or missing, it can cause what you're describing.

It is still there, but I don't know how well it works because the heat generated on the belts causes the glue to melt. Perhaps I need a new pad?
Do you know if the belts can be re-glued?

No idea on the gluing bit, never tried it

How old are the belts? It may be the humid weather has got to them. Were thay on the right way round?
We have one of them at work and I have borrowed it a few times. Never been a problem with it. Real beast of a machine and the only real hand held belt sander out there.
Regards
John

Have you checked the bearings?? most belt operational tools chew thru belts when bearings a re tight or seized

Considering the machine had been serviced last year, bearings and brushes, greasing etc, considering the graphite pad and it's underlay are both there and in good nick, I called Norton for some information.

This is what they told me.

The belts are glued with polyurethane glue, the same used for metal work belts and the glue does not give with heat or anything else.
However.

It only lasts some 3 years before it gets brittle. Once it is brittel it gives in a few minutes of use.
So his advise was to chech the numbers on the belt. They relate to time of belt manufacture but he told me they are glued into belts for sanding machines within 6 month or less.
Besides the P40 or P80 that is the grit of the abrasive, there is another set of 4 numbers that are the year and the month, so 0906 is June 2009.
I checked my belts and they are from 2006. So forget it.
I actually checked my local Mitre ten and found that the 4"x24" were all 2006 and even 2004.
Lesson learned, look for the date on the belts and don't buy anything that is more than one year old or you are throwing your money away.

You might be pressing down to hard. They don't need a huge amount of pressure to work, as they are fairly heavy anway.

thanks for the great advice marc.
i was not aware of the date on the belts.
i will certainly look for it in the future.

cheers, justin.

Found this problem the hard way quite a few years ago - old belts, old glue = no go - ended cutting them up [higher grits] for use on a sanding block. However, I believe that C'Tec has some glue available which some people use to make up their own belts from rolls of sandpaper. I have not done this myself.

Regards,
Bob

Originally Posted by Marc

Considering the machine had been serviced last year, bearings and brushes, greasing etc, considering the graphite pad and it's underlay are both there and in good nick, I called Norton for some information.

This is what they told me.

The belts are glued with polyurethane glue, the same used for metal work belts and the glue does not give with heat or anything else.
However.

It only lasts some 3 years before it gets brittle. Once it is brittel it gives in a few minutes of use.
So his advise was to chech the numbers on the belt. They relate to time of belt manufacture but he told me they are glued into belts for sanding machines within 6 month or less.
Besides the P40 or P80 that is the grit of the abrasive, there is another set of 4 numbers that are the year and the month, so 0906 is June 2009.
I checked my belts and they are from 2006. So forget it.
I actually checked my local Mitre ten and found that the 4"x24" were all 2006 and even 2004.
Lesson learned, look for the date on the belts and don't buy anything that is more than one year old or you are throwing your money away.

Great info Marc.

I bought a pack of belts last year from an old hardware store in Brunswick Melbourne. The pack was old and very faded and the belts only lasted a matter of minutes. I just put it down to being a junk brand and went and purchased another brand from elsewhere. Will now check the dates on future purchases.

Originally Posted by Marc

I have an old Makita belt sander, you know the big ugly 100x610 belt sander you can sit on it and and race others.

Ahhh... Trade school memories in the corridors. Belt sanders hooked up to a couple of long extension leads and $5 wagers on whether Makita's or Hitachi's were quicker. Great fun until the teacher came back and caught us.

Hi all,

the Makita 9400 belt sander range is among the best machines ever. Efficiency and longevity (of both machine and belt) is best when operated under its own weight only. Pressing the machine down is not the intention, this causes an excess of heat in all mechanical parts involved. After three minutes of use, is it normal for the motor, the drive belt, the gear case, the hind roller and the gliding sole between machine and belt to have heated up to some extent. At nominal load and with a non-clogged dustbag, however, a large part of that heat is dissipated by all metal cast parts and the dust suction and motor fan airstreams. The 9400-series has good motor cooling and good dust suction and -like you said- a copious metal content, so if the entire machine heats up after a few minutes only, something is wrong.

Belt glue joints are known to deteriorate over time, due to oxidation and air moisture fluctuation and UV-light. When pressing down the machine, the heat and the highly increased torque pulling at the belt and its joint, can also make it snap much earlier as designed.
Then there is the peeling off of the glue joint when the belt is used in reverse of the recommended arrow direction, but that reason is so "novice" that we can skip it here. For any more reasons, i could only come up with glitches somewhere in the belt track, like the belt edge running along something sharp and making it fray. Check the entire machine's lower half when no belt is fitted (burred details, any parts of the gliding sole clamping bar sticking out, wear spots on the gliding sole itself, worn ceramic buffers, any telltale signs with bits of snagged linen thread, also check the friction of the front roller and switch on the machine no-load without a belt and determine if it runs really full speed and friction-free. Also check the noise).
The 9400-series are of a straightforward conventional construction. Rugged, simple, no troublesome bits like intermediary angled gears or motors built in to such extent where they clog up and quickly overheat. They are my favourite sanders, generously laid out and mechanically sound. The only belts ever snapping on my 9402 were old used ones who had it coming. And that happened twice in 15 years, in which the machine has worked through scores of belts of all sorts.



greetings

gerhard

I had this problem with a Ryobi BE 424 100 x 610 out of Japan. Still reckon the build quality and flat top make it one of the best machines around. The heat was coming from the front roller which has oiless metal bearings. The drive roller at the back are rubber and don't transmit the heat. I gave mine a good clean up and sprayed the axel with some silicon lubricant. Seemed to do the trick.

Hi Damien,

you mentioned that machine before, it is indeed very good and huge value for money. AEG had Ryobi made some belt sanders from them, in the 80's during the EPTC-Daimler-era, when they realised that for sticking to quality, you don't necessarily have to rely on expensive Mafell designs. Ryobi also makes excellent printing presses, so they should know about casting and machining and adjustments precision. Ryobi used to make several other very good machines, like a heavy orbital sander (resembling the Elu MVS47), a heavy drill (resembling the Makita 6300-4) and a very nice router (a halfway cross between the Makita 3612BR and the Hitachi M12). They also made a very nice big rotary hammer and a large circular saw. All those beautiful machines are gone now. And look what they carry nowadays, what a loss and pity.

By the way: since you also use lots of German tools and accessories; have you ever experienced a sanding belt snapping apart just because it was more than 5 years old? I never have; unless those belts had seen periods of serious use. Now and then i take unused belts that came with machines who are decades old as an emergency reserve, when my stock of recently purchased belts has run out. You'll probably know them, brands like the good old Klingspor or VSM sanding stuff that came with the AEG HBSE100 or the Elu MHB90. They've never snapped on me. And now and then i saw manufacturing lot numbers on them, but seldomly a clear production date.

So what it is with the above mentioned belts that snap after just 5 years of storage, in unused state? Is polyurethane bonding really the best alternative? PU is known to turn brittle when exposed to UV-light (its colour turning yellow is a telltale sign of deterioration) and to dryness, and is known to turn weak when subjected to heat and intense shape changing (there is a lot of that going on during belt sanding; apart from pulling torque there is also the constant changing between bending around rollers and stretching again).
On the other hand, is must admit i don't know what type of adhesive was used on the old belts from Klingspor and the likes. I'll have to look that one up, but maybe you already know. If it turns out to be PU as well, i stand here with egg on my face. But then; why don't these old belts snap so quickly as opposed to the modern ones mentioned above?

thanks and greetings

gerhard

Looked it up. The conventional way of sanding belt bonding is the use of nitrile rubber (a synthetic rubber copolymer of acrylonitrile and butadiene). This substance is also used for seal rings and 0-rings (in that case with some additives, like carbon). For bonding belts, the seam of the two linen ends with the copolymer in between is pressed very tightly and heated up to 170 degrees C. The rubber compound -when fluid- will not only fill every crevice between the fibres but will probably even penetrate into parts of the linen fibres themselves. The temperature, pressure and bonding time are all critical to produce a seem mechanically strong and lasting enough.
No private person without the proper machines could copy this procedure at home, so it doesn't pay to make your own belts from stock sold on rolls.

That seems to clinch it: no PU on the vintage sanding belts and hence their longer shelf life.