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I have a 150mm Makita Random Orbital Sander commected to a small Electrolux vacuum cleaner.
The problem is that when using the sander, it leaves small spots which look like oil on the workpiece. They don't wipe off easily
Can anyone please suggest the possible cause of this? Happens every now and then.
How old is it, how often has it been serviced, sounds like grease has broken down and turned to liquid and consequently running out of the machine or maybe it has been over greased/oiled and the excess is escaping. Time to give it a good service
It could also be that the bearing is on its way out and is getting hot. This melts the grease and it leaks out. I would replace the bearing as a routine precaution.
Thanks China, never been serviced since new, about 6 years old. Never knew that the bearings needed servicing, assumed that they are sealed. Today I just took it into the local service centre and they could not find anything wrong with it, without pulling it apart. Said the bearings were good. they sanded some timber without any problem.
I was sanding a 1:2 shellac:metho mix that had been applied to open grained oak timber, using a 240 grit sanding pad. The shellac had been applied about an hour earlier, and it is a hot day ( 30degC) here.
I am wondering if the shellac in the deeper pores may have melted and shown up as spots
I have just used the sander on a sheet of MDF - no spots appeared anywhere
Have had a closer look a the timber. You can see the 'spots' are centred on a pore. Photo attached shows the sanding disc used, with the little pieces of red spots, which presumably are the raised blisters.
I have trouble with cedar and oak timber previously when using oil. It tends to blister, and needs rubbing out ever 1/2 hour. You can see my post on that here. Looks like much the same problem, except that you cannot rub it over every 15 minutes as the shellac hardens much more quickly.
Looks like I need to let the shellac dry for much longer before sanding.
Attachment 441663
Of course not! The probability of any machine leaking oil onto a workpiece varies directly with the cost and beauty of the timber :rolleyes:Quote:
Originally Posted by Dengue