Thread: Super Cheap Auto / Blackridge Air Die Grinder Yay or Nah?

This is my pump Bob i'm not sure if its single or dual piston but its a 1.six5kw motor it doesnt say what oil to use https://www.pilotair.com.au/wp-conte...ET-UPdated.pdf

Baron ugot an absolute deal on that electric die grinder lucky bugger!

Originally Posted by gazza2009au

This is my pump Bob i'm not sure if its single or dual piston but its a 1.six5kw motor it doesnt say what oil to use https://www.pilotair.com.au/wp-conte...ET-UPdated.pdf

Baron u got an absolute deal on that electric die grinder lucky bugger!

Thanks Gazza,

I bought it to replace the Dremal style grinder that I use as a toolpost grinder.
Another of those round toit jobs

Bob the Pilot Air web site recommends ISO 100, ISO 150, the oil i am running in the pump is ISO 68 i will look into what those numbers mean but can u elaborate a bit on where i am going wrong with the oil? to thick to thin etc?..

Originally Posted by BaronJ

Thanks Gazza,

I bought it to replace the Dremal style grinder that I use as a toolpost grinder.
Another of those round toit jobs

I am always stripping screw heads and bolt heads mate so this nifty little die grinder can either reshape a bolt head to grab it with pliers or grind it off for welding its the best little tool i have needed for a long time just wish it was portable with a very long lasting battery but that's a wish lol

Gota love pnumatic die grinders. I would not be without them.
DSC06296 e.jpg

To run even a small die grinder you need at least 10 cfm (free air delivery. Not to be confused with piston displacement that manufactures use to quote their compressor sizes).You can get away with less but then you are waiting a lot of the time for thecompressor to catch up. I`ve got 20 cfm and that keeps everything running nicely.

I use to have an electric die grinder for site work as air was not always available but some A-hole liked it better than I did. Hitachi, I still rate these as the best electric on the market. Never did replace it.

I still have a Dremel, they have their uses but they are really only a toy.

With bits, if your doing a lot of alley single cut aluminium bits (not to confused with single cut steel bits) are the way to go. I usebee`s wax as a lube. With steel (brass or what ever) double cut are the way to go. They do not bounce around as much and remove more material.

In pic LHS bit is single cut for ally, Very course. RHS is double cut

DSC06299 e.jpg

Back in the days when I use to service compressors 30 wt was pretty much the standard oil to use. Iso 68 if we had nothing else. I have been using 15W40 diesel engine oil (same as my ute) for 20 years now, never had aproblem.

Tony

When i had 90psi at the tool from the 10.8cfm compressor the die grinder knocked the peek off that 90psi really fast probably 8 seconds are u can hear the speed slow down but it still remains powerful for around 25 seconds than it just sits at a fast pace and tapers off in power i found it jumped around at the lower rpm/psi range but was easier to control the cut, at full power it was way to easy to gouge

I have some diesel oil i might try that tomorrow i looked up the oil i have 68 in it which is thinner viscosity than the 100 and 150 the manufacturer specify so i cant explain why the pump is struggling, one would think thinner oil less drag unless the oil 'floats' the crankshaft and it may be binding with the thinner oil? Possibility

I could not find any actual flow figures for your compressor but I am thinking that 10.8 cfm is piston displacement.
The old rule of thumb use to be 3/4 of piston displacement would give you roughly an air delivery figure.
Also with a 1.65kW motor I`d expect this to be supplying about 7cfm @ 90 psi.
This would explain why the grinder speed is dropping off so quickly.

Are there any air flow figure given in the instructions that came with the grinder?

I dont actually have a regulator to see the psi there is a gauge on the tank and i remember having a regulator at the end of the hose previously and it was reading around the 90psi mark maybe 95psi

I just checked the manual it says 128 litres per minute i have about a 50-60 litre tank plus i have the tinest grinder nick in my hose so a cery small portion is leaking from the hose nothing major just like a leaking fitting

Ok,
Tank size is irrelevant. With a larger tank it takes longer before the comp starts but it also takes longer to fill.
At the end of the day what goes in is what comes out.

"plus i have the tinest grinder nick in my hose so a cery small portion is leaking from the hose nothing major just like a leaking fitting"


You would be surprised how much air is lost through a small leak.

A good test is leave the compressor fully charged and off to see how much it leaks down. (A good comp should take days if not weeks to bleed right down). Then plug your line back in and see how long it takes to bleed down.


128 l/min, about 4.5 cfm. I`ll assume (not a good thing) that this is what`s called its average air consumption. Actual air consumption at load will be at least twice this figure. If those figures are correct that makes an economical grinder. My small CP pencil grinder uses nearly that much. Wander what the watt rating is for the Ryobi?

Tony

Originally Posted by bts

I could not find any actual flow figures for your compressor but I am thinking that 10.8 cfm is piston displacement.
The old rule of thumb use to be 3/4 of piston displacement would give you roughly an air delivery figure.
Also with a 1.65kW motor I`d expect this to be supplying about 7cfm @ 90 psi.
This would explain why the grinder speed is dropping off so quickly.

Are there any air flow figure given in the instructions that came with the grinder?

Looks like you guessed about right. The data panel here:
https://www.pilotair.com.au/product/...ors-tm-series/
quotes Piston Displacement 10.7 cfm and FAD as 6.5 cfm and maximum pressure 145 psi. It doesn't specify the pressure at which the 6.5 cfm is delivered, so possibly at 145 psi? It does say performance measured to AS4637. Does the standard specify the pressure at which FAD is delivered?

Frank

Guys the Pilot Air Compressor is just not panning out i have owned it for a few years now probably about 5 years i think its time to cut my loss and buy another air compressor, Today i changed the oil to ATF i aligned the belt and pulleys but its still making that sequel and the up and down revs and it almost stalling before hitting air cut off point than speeding up again out of no where to top it off i just snapped my plastic pvc hose in 3 pieces

about to look online for one or possibly 2x 50 litre compressors to link together

Maybe the compressor valves are leaking, could be a cause of your semi stalling.

Does the belt have a smooth shine to it? New belt may be in order.

Generally the finger valves on the compressor don`t offer to many problems. Though pulling them out can give a chance to clean them up for better sealing, without having a set a gaskets on hand I would not go there.

In the air line from the comp to the tank there should be a non-return valve. Depending on the type I have had problems in the passed with these sticking leaking air back and loading up the compressor.

Keep going with this one. Get it going and then buy another to give more air. You will need the money saved on buying two for the bits you need to connect two together and get the best out of them. That and the new air tools you will want to buy now you have the extra air.

Tony

I blocked off the snapped hose and powered up the compressor and got a video of it

https://www.youtube.com/watch?v=g5FU9XpgIw4

i pulled the one way check valve a part and it seems one of the seals above the button inside the valve had perished i blew thru the valve with my mouth and it seemed to work ok even with the perished seal

I keep meaning to ask, do you have a pressure gauge mounted somewhere to see at what pressures the comp is cutting in and out at and at what pressure things start to go wrong.

Tony

I`m afraid blowing through it does not mean much. Remember 145 psi takes a lot of stopping.

Just watched the vid. Sounds like the compressor is battling head pressure. Replace the seal in the non-return valve and see how it goes.

Tony