Author Topic: Tube for blowing out 8mm holes  (Read 1136 times)

Offline andrewmc

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Tube for blowing out 8mm holes
« on: August 09, 2019, 11:16:58 am »
If there was an award for most niche equipment question, I suspect this would be in the running...

What is the best tubing for blowing out 8mm drill holes? Ideally I guess you want something thin-walled with roughly the same surface area inside the hole and between the tube and the drill hole. In any event it is going to be much harder to blow down than a larger bit of tubing (which won't fit in an 8mm hole). If you were going to massively overengineer it, you could put a short 4mm (or whatever) stub on a bit of larger tubing...

PS there are a set of nice Raumer double expansion bolts in a cave I have bolted (abroad) where the holes weren't blown out. The bolts that weren't blown out have all crept out significantly further before biting (and violated the Raumer 'good bolt' criteria) so it does make a difference!

Offline Benfool

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Re: Tube for blowing out 8mm holes
« Reply #1 on: August 09, 2019, 11:38:57 am »
drinking straw?

B

Offline phil

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Re: Tube for blowing out 8mm holes
« Reply #2 on: August 09, 2019, 12:21:46 pm »
Airline tubing from aquarium filters / pumps.  A couple of quid from Wilco's

Offline langcliffe

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Re: Tube for blowing out 8mm holes
« Reply #3 on: August 09, 2019, 12:45:05 pm »
I use this (and also for larger holes). It's a short length of flexible tubing bought from an aquarium shop, attached to some larger diameter carbide tubing. The latter allows me to get a good supply of air through to the flexible end.


Offline TheBitterEnd

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Re: Tube for blowing out 8mm holes
« Reply #4 on: August 09, 2019, 05:50:47 pm »
Big gauge Earth sleeving as used by electricians
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Offline PeteHall

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Re: Tube for blowing out 8mm holes
« Reply #5 on: August 09, 2019, 10:13:16 pm »
Bit overkill perhaps and a bit bulky for caving, but we used these at work and very effective. Generally known as the "Big Puff"

https://www.hilti.co.uk/c/CLS_FASTENER_7135/CLS_ACCESSORIES_TESTERS_7135/CLS_CLEANING_ACCESSORIES_7135/r3557

Alternatively, what about some 6mm pneumatic hose? Right size, semi-rigid and very tough.
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Offline andrewmc

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Re: Tube for blowing out 8mm holes
« Reply #6 on: August 10, 2019, 07:48:53 am »
Bit overkill perhaps and a bit bulky for caving, but we used these at work and very effective. Generally known as the "Big Puff"

I've got a cheaper variant of that which I've used before but the tube doesn't fit down an 8mm hole; is the tube on the Hilti one small enough? I think I'm going to construct some sort of fat tube/metal straw hybrid tube and also get some airline tubing based on suggestions.

Offline SamT

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Re: Tube for blowing out 8mm holes
« Reply #7 on: August 10, 2019, 01:58:26 pm »
You blow out capping holes???

Done a lot of capping but never bothered blowing out the holes.   :shrug:

Other methods - yes. Capping, cant see the point really.

Offline SamT

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Re: Tube for blowing out 8mm holes
« Reply #8 on: August 10, 2019, 01:59:08 pm »

Actually - you never mentioned capping ...  :-[   :chair:

Offline andrewmc

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Re: Tube for blowing out 8mm holes
« Reply #9 on: August 11, 2019, 12:23:04 am »
You blow out capping holes???

Done a lot of capping but never bothered blowing out the holes.   :shrug:

Other methods - yes. Capping, cant see the point really.

I don't know about capping, but I have previously been told it is important for plug and feathers as otherwise the dust absorbs the expansion force (as it is softer)...

Offline Cave_Troll

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Re: Tube for blowing out 8mm holes
« Reply #10 on: August 12, 2019, 11:18:12 am »
I'd have thought the dust only absorbs a bit of force until it's compressed and the force is transferred.
even then it's not really "absorbing" the force.
imagine laying on a foam mattress. your weight (force) is still transferred to the floor.


Offline Ian Ball

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Re: Tube for blowing out 8mm holes
« Reply #11 on: August 12, 2019, 12:36:02 pm »
The princess and the pea analogy   :thumbsup:


Offline Pitlamp

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Re: Tube for blowing out 8mm holes
« Reply #13 on: August 14, 2019, 08:20:39 am »
Langcliffe mentioned flexible tubing; in case it helps to know (for those in the Dales) Ashfield's DIY in Settle sells a wide range of diameters of flexible PVC tubing by the metre.

http://www.settlediy.com/

Offline langcliffe

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Re: Tube for blowing out 8mm holes
« Reply #14 on: August 14, 2019, 04:45:28 pm »
Langcliffe mentioned flexible tubing; in case it helps to know (for those in the Dales) Ashfield's DIY in Settle sells a wide range of diameters of flexible PVC tubing by the metre.

http://www.settlediy.com/

I remember now - that's where I got it from!

Offline Joel Corrigan

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Re: Tube for blowing out 8mm holes
« Reply #15 on: August 15, 2019, 10:15:25 am »
Andrew: I recommend a pink Curly Wurly straw as thats right up your street ;-)  Failing that (and as others have mentioned) some skinny flexible gas pipe is ideal. Make sure it’s long enough so u can clear the hole from a bit of a distance (maybe half a metre or longer depending on how athletic & “reachy” your bolting is) & bear in mind that over time you might chop bits off that have become blocked so thats another reason to start off longer than you think.  Then attach some skinny bungee to it near the end (secure with a barrel knot & duct tape). Options: make a big bungee loop that goes over my head but that can become a snag point so possibly have a single length with a teeny accessory krab to clip to your chest harness instead. Most of the time the pipe gets stuffed down my oversuit. On your travels can you pick up a few metres for the Dachstein, please?  Make sure it doesn’t get brittle in the cold but presumably someone switched on in a hardware store will be able to advise.

Offline Andyj23UK

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Re: Tube for blowing out 8mm holes
« Reply #16 on: August 15, 2019, 06:19:59 pm »
car parts outlets : iether fuel of " window washers " hose

Offline braveduck

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Re: Tube for blowing out 8mm holes
« Reply #17 on: August 16, 2019, 12:11:11 am »
Today went to Ashfields DIY in Settle .They sell plastic tube from 3mm to 15 mm by the Metre .
For 30p I got the perfect blowing out tube ! :clap2:

Offline Pitlamp

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Re: Tube for blowing out 8mm holes
« Reply #18 on: August 16, 2019, 08:15:19 pm »
Today went to Ashfields DIY in Settle .They sell plastic tube from 3mm to 15 mm by the Metre .
For 30p I got the perfect blowing out tube ! :clap2:

There you are - I told you so!   ;)