Advice needed on my first compressor

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wobblycogs

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For a while now I've been considering buying a small compressor for the workshop but I could do with some advice. The one I'm current considering is this from Axminster (AXMINSTER CRAFT AC21C, 21 ltr, 1.5kW). In the workshop it'll be used mostly for nailing and dusting which I'm sure it's capable of but...

I have a job around the house right now (window restoration) that would benefit from running a right angle die grinder / 50mm sander. The one I'm looking at is this but they all seem to be much of a much-ness in that they consume a decent bit of air (seems to be about 100 l/m @ 6 bar or more if possible). I know the compressor I've linked to isn't even close to capable of running this tool continuously but it is light enough that I can carry it up two flights of stairs to get it closer to the job. What I'd like to know is will that compressor run that tool in short bursts? I don't have a huge amount to sand and if the job takes two hours instead of ten minutes it's not that important to me as I'm not getting paid anyway!

I've got a multi-tool and I've used that with the triangular sanding pads in the past but, imho, they are terrible. The vibrating motion seems to brush the fuzz on the paper so it just falls off the velcro after a couple of minutes. I don't know, maybe just accepting the multi-tools is a bit rubbish as a sanding is the best option, it's certainly the cheapest option. Thoughts? Thanks.
 

Spectric

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That tool may not be the easiest to control, the disc does protrude out a fair way and with a shorter distance you have more control unless there is a way to hold it closer to the pad.

For compressors take a look at SGS engineering, I brought one and it is great for the money with 24 litre tank but if you get SGS 50 Litre Direct Drive Air Compressor - 9.6CFM, 2.5HP, 50L which is 9.6 CFM then you should be ok. This sander is 4.5 CFM so you would be ok.

 

wobblycogs

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Thanks, I'm torn between a sander and a right angle die grinder. Considering they are only about £30 maybe I'll just get one of each and see which I prefer, considering how much this house has already cost me I won't even notice the cost :-(

I'm seriously tempted with the 24 litre version of that compressor, 2.5hp is going to help it deliver some serious air. If I didn't have to carry the thing up the stairs I'd definitely go with the 50 litre but it's 38kg and I'm not as strong as I once was.
 

flh801978

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another thing to consider ...the noise from that type of compressor will wear you out in short order..you will be always wondering when its going to start up and be thankfull when it stops

Ian
 

porker

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I think you will struggle to run a die grinder from that compressor. Even the one @Spectric mentions will be pushing it. Die grinders are one of the most air hungry tools. I have a little 12ltr compressor that I can lug around the house and its great for my 18g nailer, dusting and blowing up tyres. I also have a 2HP 50L one similar to @Spectric and it won't run my die grinder in a satisfactory way. My die grinder may be slightly larger but looking at the Q&A someone says it takes a 14CFM compressor or 9 CFM FAD. Neither of these compressors are close to that and even for short bursts I think you will be frustrated. Also be aware, they are very noisy. In your position I would look at corded or battery solutions.
 

porker

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I see it state 4.5 CFM. If this is the case then maybe a 2HP compressor would drive it but the smaller one definatelty not. I would double check the consumption because I have my doubts. Also compressor manufacturers state the CFM which is the swept volume of the cylinder but the FAD (free air delivery) will probably be about 30% less and this is what the tool needs to be specced to.
 

clogs

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air line is cheap....buy a decent comp and leave it outside or in the shed....
I reg run an airline 50m plus....it does have a huge comp behind it tho....
my little comp is to small to blow up a tractor tyres....and long airlines saves me using a fork lift to move the big'un about....
oh and it's 3 phase.....not quite what ya want on the end of an extension lead...
 

wobblycogs

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Finding decent air consumption rates for most of these tools is hard. It seems sanders are generally lower consumption than die grinders though. I was looking at die grinders because I don't particularly want the random orbit feature but it's not that important.

Could you please check I'm understating this correctly, the CFM value stated is what the machine sucks in (swept volume) but the free air delivery is what it pushes out (under pressure). Looking at the Axminster compressor I linked to originally because it has decent figures it's listed as 6.64CFM and it'll put out [email protected] so it's not even close to enough to run the sander @Spectric mentioned. The 50 litre compressor they mentioned though would probably just about manage it assuming the same roughly 50% drop from 9.6CFM to just over 4.5CFM @ 6 bar. That makes a lot more sense now.

As I say I've got a corded multi-tool so maybe I should just go with that. I hadn't realized just how large a compressor is needed. Seems crazy that you need a two or three HP motor and a decent sized tank to run a little hand held tool. I'm open to alternative suggestions.

@clogs wow, air line is far cheaper than I expected. That might be a solution to the problem. I needed a good few meters for the workshop anyway.
 

porker

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I think you have that about right. 6 bar is 87psi and most tools run at or above this in my experience. A 50% reduction from quoted CFM seems high but if you assume this you would be safe. The reason I have 2 compressors is that I like the 12L one for nailing which it does easily and it is portable. Even a smaller compressor will run an air nailer with ease. Its just some tools take a lot of air and even allowing for intermittent use can be very frustrating. The noise from a lot of direct drive units is loud as well. When I finally get round to my workshop build I will look for a 200Ltr 3HP belt driven unit which should do what I want and they seem much quiter. @petermillard did a recent video on a cheap nailer setup that is worth a watch but for sanding I would go the multi-tool or delta sander route. I do mostly DIY house renovation and that would be my approach.
 

wobblycogs

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Everything I'm reading says you're spot on right, @porker. If I continue down this path I'm going to end up with a compressor that's bigger than I need for things like nailing and dusting and too small for sanding. Funnily enough it was the @petermillard video that got me to properly look into this.

Time to buy some new sanding pads for the multi-tool, at least they have come down in price over the years.

Many thanks for the help everyone.
 

Trainee neophyte

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I have a 3hp single phase generic chinese compressor with 100 litre tank. It runs an orbital sander @ 90 psi, but the motor runs continuously. It is monstrously loud, too. I'm actually thinking of investing in an electric sander just because of the noise, although the actual sander is such a tiny, light thing it is a joy to use.
 

sometimewoodworker

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I know the compressor I've linked to isn't even close to capable of running this tool continuously but it is light enough that I can carry it up two flights of stairs to get it closer to the job. What I'd like to know is will that compressor run that tool in short bursts? I don't have a huge amount to sand and if the job takes two hours instead of ten minutes it's not that important to me as I'm not getting paid anyway!
The compressor running out of air will not just extend the job, it may make it impossible. You want as short an airline as you can get, but if you have a honking great compressor some decent big ID superior air hose for the majority of the distance then you can run 5 ~ 10 metres of more flexible on the end of that.

I routinely run at 20 metres from my compressor and get excellent flow and pressure, but I do have a 3 cylinder compressor that makes the lights flicker when it’s running.
 
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