Yet Another Cycling Forum
General Category => The Knowledge => OT Knowledge => Topic started by: toontra on 12 July, 2023, 08:08:36 am
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I need to restore some ornate iron railings that are caked in paint and corrosion going back centuries - literally. I was puzzling for a long time on how to go about it and then stumbled on needle scalers. They look absolutely ideal, but they use compressed air, about which I know nothing ;D.
Anyone any idea on what sort of compressor I'd need to power something like this? -https://www.amazon.co.uk/gp/product/B09YPS48LL/ref=ox_sc_act_title_1?smid=A39FZ0OKQH7LY&psc=1 (https://www.amazon.co.uk/gp/product/B09YPS48LL/ref=ox_sc_act_title_1?smid=A39FZ0OKQH7LY&psc=1)
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A chum got one with a decent tank for around 80€ - you'd need that for semi-continuous use. I have a wee one for my nail gun but it'd run out PDQ with a scaler. You can get lots of other tools to run off them, e.g. impact wrenches for car wheel-nuts. Good thing to have.
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Cheers - any idea on the spec I should be looking for?
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One like this should be more than adequate..
https://www.machinemart.co.uk/p/clarke-monza-15hp-8-bar-635cfm-portable-oil-fr/
Godd enough flow rate, which is what's important for your application. I don't think you'll need one with a reservoir.
ETA: You'll need to check compatability of fittings, or more likely get some adaptors, to connect source to scaler.
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I'm going to have to disagree with raflecher on this one. No reservoir and a flow rate less than what the tool uses on full power will stop you using the tool to it's full potential, even briefly.
This https://www.machinemart.co.uk/p/clarke-x-pro-cat164-air-needle-scaler--hammer-/ (https://www.machinemart.co.uk/p/clarke-x-pro-cat164-air-needle-scaler--hammer-/) is a similar device that states 4 cfm* at no load and 13 cfm at full load, so I would guess similar values for the one you are looking at.
To get a compressor that will keep up with that under load is quite expensive. You could probably get away with something with a reservoir as you won't want to hold the trigger down for long periods at a time. For your convenience, air reservoirs are measured in litres**
Something like this https://www.machinemart.co.uk/p/clarke-tiger-8260-2hp-24-litre-air-compressor/ (https://www.machinemart.co.uk/p/clarke-tiger-8260-2hp-24-litre-air-compressor/) creates 7 cfm of air, so will be 6 cfm short of keeping up with the tool at full power. The 24 litre tank can be pumped to 8 bar, and has a pressure regulator to limit the pressure. If the air tool is running at its maximum of 6.2 bar, the tank will drop by 1.8 bar from full to when the pressure to the tool starts to drop. 1.8 bar in a 24 litre tank is 43.2 litres of free air, or 1.5 cubic feet. If 6 cfm is coming from the tank, that will last about 15 seconds of full power running and take just under 15 second for the compressor to make that up when the tool isn't in use.
I would say that would be adequate.
Wear ear defenders and gloves. Compressors are noisy and get hot. Air powered tools are noisy and get cold if used hard. The exhaust air can be well below freezing.
*Cubic feet per minute - arcane measurement of compressed air consumption, measured as atmospheric air not compressed.
**Not-quite-SI unit of volume, measuring the volume of compressed air in this context.
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I don't think you'll need one with a reservoir.
Depends on how much you value your hearing. Something with a reservoir will cycle on and off according to demand. A portable compressor like that will just run, and you'll find yourself subconsciously rushing things so you can turn it off sooner and stop annoying the neighbours.
FWIW, I have an obnoxiously loud portable compressor with a 5 litre reservoir (https://www.verkter.com/air-compressor-stanley-air-boss.html). Which is fuck all in terms of running air tools, but just the thing for tyre inflation (particularly tubeless) and blasting fluff out of the crevices of electronic equipment.
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Thanks all - very informative.
Diver300 - just the sort of info I need. Tempted just to go for the gun and compressor you linked to. Anything else I need - hose, etc?
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Something like this https://www.machinemart.co.uk/p/clarke-tiger-8260-2hp-24-litre-air-compressor/ (https://www.machinemart.co.uk/p/clarke-tiger-8260-2hp-24-litre-air-compressor/)
That's similar to what my chum has. I'd recommend getting an extension hose as well so that you can put it a bit further away from where you're working. Even my wee electric one is a noisy bugger.
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Thanks all - very informative.
Diver300 - just the sort of info I need. Tempted just to go for the gun and compressor you linked to. Anything else I need - hose, etc?
No idea. My air consumption calculation skills come from something to with my username. I have no idea if hose fittings on industrial equipment are standard or not.
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I'd recommend going to a DIY emporium and getting advice on hoses and accessories. I started looking through that Machinemart site and found it a bit of a maze.
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I'd recommend going to a DIY emporium and getting advice on hoses and accessories. I started looking through that Machinemart site and found it a bit of a maze.
Yep - probably a good idea.
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I have no idea if hose fittings on industrial equipment are standard or not.
Ah - I know this: Ostensibly yes, but the tolerances are so awful that SOP is to buy all your fittings from the same manufacturer (preferably just buy a set with a few of each type) so they seal properly when coupled. If you're buying a half-decent compressor, it's worth having a tyre inflator and a blowing-air-at-things nozzle, as well as whatever proper tools you want to use, so you'll want a few of the male[1] fittings. Cheap compressed air fittings are a false economy, as they'll tend to leak, and when you get hacked off and buy better ones you'll likely have to replace the one on all your tools for compatibility.
[1] Male fittings are just carefully-shaped bits of metal, with either a male or female ?BSP thread to connect to the tool. Female fittings have the mechanism that that seals when disconnected. So the compressor outlet would have a female fitting, and hoses would have one of each.
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Thanks all - very informative.
Diver300 - just the sort of info I need. Tempted just to go for the gun and compressor you linked to. Anything else I need - hose, etc?
Ear defenders.
J
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Thanks all - very informative.
Diver300 - just the sort of info I need. Tempted just to go for the gun and compressor you linked to. Anything else I need - hose, etc?
Ear defenders.
J
;D Yes. I strongly suspect there's a lot of lead paint buried in there so probably a respirator too!
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Kinda makes you nostalgic for the old wire brush stuck in a Black & Decker, doesn't it?
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Kinda makes you nostalgic for the old wire brush stuck in a Black & Decker, doesn't it?
Tried that already ;) - didn't touch it.
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My contribution is similar:
Compressors other than special expensive ones are bloody loud.
Needle guns are bloody loud.
Needle guns use a lot of air, so really check consumption against compressor output AT THAT PRESSURE, not free air delivered.
They are not nice to use, so wear shock absorbing gloves, and you will only want to do it in shortish sessions.
The suggestion about an extension lead, and a long air hose, is excellent, get the damn thing away from you.
Proper ear defenders, seriously, really are absolutely vital.
Have I mentioned its a loud business?
Based on practical experience with a hobby type compressor with a reservoir, a long extension lead, and a long air hose. I am quite deaf, and the noise of the compressor is still oppressive.
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Needle guns use a lot of air, so really check consumption against compressor output AT THAT PRESSURE, not free air delivered.
Air consumption or compressor flow rates are always measured as "free air" as in volume at atmospheric pressure, so a compressor delivering 5 cfm at 4 bar (gauge), so 5 bar (absolute) will only be 1 cfm of compressed air, but that figure of 1 cfm would never be quoted.
However, a compressor's free air delivery will depend on the delivery pressure. A compressor that delivers 5 cfm at 4 bar (gauge) would deliver more, up to twice as much, when there is no output pressure. That is just like the fact that getting the first 10 psi into a bike tyre is much easier than getting the last 10 psi.
Wombat is right that the rating for a compressor needs to be found at the pressure you will be working at. If there is a reservoir its maximum pressure is significantly higher than the pressure being fed to the pneumatic tool, so the CFM at the maximum reservoir pressure is what you should really look at. You don't want something that slows down a lot as the reservoir gets full.
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Would it not be better to hire the whole kit? That way someone else has done all the research into what works and what doesn't and which fittings you need for the gun and hoses. It probably won't be cheap and you won't have another toy to play with when you have finished, but you won't make an expensive mistake and get something which only half does the job.
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The hire idea was appealing. Rang around and apparently there are electric needle guns - for example the Hilti TE300 Light-Duty Needle Scaler. That would simplify things greatly - only need to add a 110v transformer. £80 for the week. What could go wrong ;)
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Even more interesting - an attachment that turns your SDS hammer drill into a needle scaler. If these actually work that would mean having a needle gun at my disposal for future use - just whang it on the Hilti.
https://davincitools.com/product/scrostatore-da-12-aghi-professionale-universale-per-qualunque-martello-elettrico-max-4-j-con-mandrino-sds/ (https://davincitools.com/product/scrostatore-da-12-aghi-professionale-universale-per-qualunque-martello-elettrico-max-4-j-con-mandrino-sds/)
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Even more interesting - an attachment that turns your SDS hammer drill into a needle scaler. If these actually work that would mean having a needle gun at my disposal for future use - just whang it on the Hilti.
https://davincitools.com/product/scrostatore-da-12-aghi-professionale-universale-per-qualunque-martello-elettrico-max-4-j-con-mandrino-sds/ (https://davincitools.com/product/scrostatore-da-12-aghi-professionale-universale-per-qualunque-martello-elettrico-max-4-j-con-mandrino-sds/)
Oooh. That is useful!!
Thanks for that.
J
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Looks like they sell these direct from the UK - https://www.amazon.co.uk/dp/B0757MVTMR/?coliid=I1VF282H87ESK7&colid=1WSCBYAKQVG8J&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it (https://www.amazon.co.uk/dp/B0757MVTMR/?coliid=I1VF282H87ESK7&colid=1WSCBYAKQVG8J&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it)
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Thanks all - very informative.
Diver300 - just the sort of info I need. Tempted just to go for the gun and compressor you linked to. Anything else I need - hose, etc?
Ear defenders.
J
;D Yes. I strongly suspect there's a lot of lead paint buried in there so probably a respirator too!
Also, I would suggest a few minutes reading about the hazards of vibration white finger and how to prevent it. I'm not certain that your activity will be a risk but aware enough to know to ask and then adopt appropriate exposure management.
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Also, I would suggest a few minutes reading about the hazards of vibration white finger and how to prevent it. I'm not certain that your activity will be a risk but aware enough to know to ask and then adopt appropriate exposure management.
Thanks Matthew - will read up on that. Looks like I'll be adding vibration-absorbing gloves to the mask and goggles. Fortunately there isn't a time restriction on this so I can do it in small sections at a time.
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anti vibration gloves are generally accepted as a waste of time. They simply lead to the wearer gripping harder, compressing the absorbent material and making little difference to the vibration.
Generally no dvice on the market should be without a vibration level. A few 8 hour days will not cause more than temporary harm evn at the highest level but common sense is to reduce as much as possible
Sandblasting is much less of a vibration risk. could that be an alternative or even commercial dipping?
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anti vibration gloves are generally accepted as a waste of time. They simply lead to the wearer gripping harder, compressing the absorbent material and making little difference to the vibration.
Generally no dvice on the market should be without a vibration level. A few 8 hour days will not cause more than temporary harm evn at the highest level but common sense is to reduce as much as possible
Sandblasting is much less of a vibration risk. could that be an alternative or even commercial dipping?
Thanks for the info. Sandblasting and dipping ruled out on grounds of practicality and cost sadly.
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I would certainly suggest keeping the hands warm and away from any exhausted air. Whilst a few 8 hour days will not be likely to cause permanent damage I would recommend probably no more than a couple of hours in the morning and then again in the afternoon in order to reduce the total daily dose.
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Needle scalers produce huge vibration doses be careful.
www.hse.gov.uk/vibration/hav/index.htm
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I would certainly suggest keeping the hands warm and away from any exhausted air. Whilst a few 8 hour days will not be likely to cause permanent damage I would recommend probably no more than a couple of hours in the morning and then again in the afternoon in order to reduce the total daily dose.
Yes - the plan would be do work in small slots. It's going to take a long time whatever the method - I've never seen Georgian railings in such a state (and I've seen some bad ones). The finials are so caked they are barely identifiable.
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Needle scalers produce huge vibration doses be careful.
www.hse.gov.uk/vibration/hav/index.htm
That page links to a handy trigger time ready reckoner. You'll need the acceleartion data for the particulat bit of kit.
<drift> A previous employer used to use GBFO hand held hydraulic breakers, which we used the manufacturer's data on to detemine trigger time. Then read the data sheet a bit more closely to find the acceleration figure quoted was when the breaker was used at only half the flowrate of hydraulic oil, which no one did. </drift>
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You've probably thought of it, but it's not in the thread yet. Disc and flap sanders. I've seen several commmercial chandleries who prefer this method to shifting paint, gunk, and over-applied stuff, including below the waterline. Reason being they dislike the abrasion and erosion of needle guns on the material, nor the effect on their staff, nor the noise for the whole place. And by the time you're down to the very fine inset details, if needed, a chisel or tile scorer will get the last bits.
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You've probably thought of it, but it's not in the thread yet. Disc and flap sanders.
Ah - no. Not heard of these but definitely interesting. Any recommendations on type?
By coincidence the SDS needle gun attachment arrived today and had its first outing. It certainly gets through the layers! It will be a laborious, noisy and messy process but will work well for the finial details. I got the smallest 12 rod version for this purpose and will proceed small sections at a time (for the neighbours' sanity as much as mine).
For the railing rods something like an angle grinder disc would be a lot quicker and easier.
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Found these to be quite good. Not sure about the brands but have used these type of abrasive wheels to clean bits of car metal. Used the ones from wilko.
https://www.toolstation.com/abracs-poly-abrasive-wheel-brush/p11419? https://www.toolstation.com/abracs-poly-abrasive-disc/p22693
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I'm having a re-think. It's going to be a long, noisy and messy business with needle guns, angle grinders, etc. and I'm very conscious of the impact on neighbours. There's no realistic way of preventing crap being sprayed into their stairwells.
Then I remembered Peelaway, a strong alkali paste which I've used successfully to remove Artex from ceilings (::-)) and on exterior stucco (from around the same period as these railings).
If it works it would minimise the exposure to the many layers of lead paint which are undoubtedly there and could slash the time and physical labour involved. I'll get a test area underway.