Date
1 - 14 of 14
Mast problem = UKAC no-show for DBN
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Neil Smith G4DBN
Lower wall clamp on my SCAM is loose because the bricks of the
barn wall have crumbled and the rawlbolts are loose, so I can't
get the dish above roof/tree height without risking the whole lot
falling on to the house. No-show for me in the UKAC SHF tonight
sorry. --
Neil G4DBN |
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Paul G8AQA
I doubt whether chemical fix will be good enough.
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Only way is to drill all the way through and put a plate on the other side. I have to do this with soft insulating blocks. 73 Paul G8AQA On 24/01/2023 20:28, Neil Smith G4DBN wrote:
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Neil Smith G4DBN
I'm aiming to fit an internal frame like I have on the winch on the wall. The wall of the barn was built before bricklaying skills had reached this corner of East Yorkshire. The inside face has steps of up to an inch between the surfaces of the bricks, which appear to have been made by someone using only their left foot, from clay they found in a ditch then fired with a candle. Not a very good candle. Foundations also appear to be an alien concept in these parts. Along with their lack of understanding about making mortar that doesn't just wash away in the rain, it means that my antennas have to be design to hold the buildings up, not vice versa. Add in to the mix the Feb 2008 Market Rasen Earthquake, which made multiple cracks in the gable of the barn. Not at all ideal. The internal frame will need grouting to spread the load otherwise the wall will crumble. I'll use engineering plastic spreaders on the relatively flat outside face and run 16 mm bolts through the wall to nip it all up. Better get the big welder fired up. Unfortunately I'm 100% tied up with machining jobs and some sponsored Youtube vids, plus I lost several trees in the recent gales and have to deal with the aftermath, so I'll try to get things fixed for the next SHF UKAC. Neil G4DBN On 24 Jan 2023, at 22:14, Paul G8AQA via groups.io <paulnick@...> wrote:
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John Lemay
Neil
You were missed last night – usually a dead cert for a contact.
Sorry to hear about the wall. They don’t make ‘em like they used to, which may be just as well !
John G4ZTR
From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Neil Smith G4DBN
Sent: 24 January 2023 22:54 To: UKMicrowaves@groups.io Subject: Re: [UKMicrowaves] Mast problem = UKAC no-show for DBN
I'm aiming to fit an internal frame like I have on the winch on the wall. The wall of the barn was built before bricklaying skills had reached this corner of East Yorkshire. The inside face has steps of up to an inch between the surfaces of the bricks, which appear to have been made by someone using only their left foot, from clay they found in a ditch then fired with a candle. Not a very good candle. Foundations also appear to be an alien concept in these parts. Along with their lack of understanding about making mortar that doesn't just wash away in the rain, it means that my antennas have to be design to hold the buildings up, not vice versa. Add in to the mix the Feb 2008 Market Rasen Earthquake, which made multiple cracks in the gable of the barn. Not at all ideal.
The internal frame will need grouting to spread the load otherwise the wall will crumble. I'll use engineering plastic spreaders on the relatively flat outside face and run 16 mm bolts through the wall to nip it all up.
Better get the big welder fired up.
Unfortunately I'm 100% tied up with machining jobs and some sponsored Youtube vids, plus I lost several trees in the recent gales and have to deal with the aftermath, so I'll try to get things fixed for the next SHF UKAC.
Neil G4DBN
On 24 Jan 2023, at 22:14, Paul G8AQA via groups.io <paulnick@...> wrote:
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Wilko
🤣 Sounds like whoever commisioned the bricklaying had better outsourced that to the folks who built Stonehenge.
Wilko PA1WBU |
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Neil Smith G4DBN
To be fair, the barn brickwork is WAAAYY better than the quality of the main house. The house bricks appear to be stuck together with sand and crushed seashells. Luckily the outside is mostly painted or rendered with a fibrous mortar that helps prevent the house from dissolving or being washed away. Like many houses for farm labourers, it was not of the finest quality in terms of materials nor workmanship. I might dig a foundation and then bolt the barn wall to the SCAM.
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Neil G4DBN On 25/01/2023 12:45, Wilko wrote:
🤣 Sounds like whoever commisioned the bricklaying had better outsourced that to the folks who built Stonehenge. |
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alwyn.seeds1
Dear All,
Neil’s post is a reminder of the hazards of rawl-bolt fixing, especially with dynamic loading such as aerial masts. Having seen one mast eventually wear away the rawl-bolt holes, causing a collapse and another one where the rawl-bolts cracked the brickwork, I have become a great fan of epoxy fixings. For reliability it is essential to clean out all dust from the hole before pumping in the epoxy. A suitably sized bottle brush, followed by vacuum cleaner seems to work well. Regards, Alwyn G8DOH _____________________________________________________ Alwyn Seeds, Director SynOptika Ltd., 114 Beaufort Street, London, SW3 6BU, England. SynOptika Ltd., Registered in England and Wales: No. 04606737 Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom. _____________________________________________________ |
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Paul G8AQA
Dear All,
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If you use compressed air to clean out the hole always shut your eyes before pulling the trigger. I have done the experiment! I have used plenty of chemical fixings and never had a failure. It is easier to use bigger bolts/studs which of course helps and it is easier to line things up as you can drill through the item to be fixed. There are plenty of versions available from the usual merchants. Regards Paul G8AQA On 25/01/2023 17:49, alwyn.seeds1
wrote:
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ian hope (2E0IJH)
One word of warning with chemical fixings, Make sure the mortar between the bricks is ok, I've had a T&K pull a brick out that had a chemical stud in it.
Ian
M5IJH Sent: Wednesday, January 25, 2023 at 8:38 PM
From: "Paul G8AQA via groups.io" <paulnick@...> To: UKMicrowaves@groups.io Subject: Re: [UKMicrowaves] Mast problem = UKAC no-show for DBN Dear All,
If you use compressed air to clean out the hole always shut your eyes before pulling the trigger. I have done the experiment! I have used plenty of chemical fixings and never had a failure. It is easier to use bigger bolts/studs which of course helps and it is easier to line things up as you can drill through the item to be fixed. There are plenty of versions available from the usual merchants. Regards Paul G8AQA On 25/01/2023 17:49, alwyn.seeds1 wrote:
Dear All, |
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On Wed, Jan 25, 2023 at 08:57 PM, ian hope (2E0IJH) wrote:
The old house down south was built with similar village-made bricks to Neil's, and dodgy mortar, so when mounting a Tennamast against the wall I asked them to make an extra-wide K bracket with a second crossbar below. That spread the load across a total of 7 fixing points at 3 levels, leaving clear courses of bricks between. I used resin anchors to avoid splitting the bricks; but they were rather new to the market back then. Even with well-cleaned holes, I still felt far from confident about the half-baked clay material itself. A useful tip from the Fischer Fixings literature was to drill clear through the bricks into the cavity, and then use the plastic mesh 'test tubes' to line the holes. These tubes are about an inch longer than the depth of the brick, with a closed end that overhangs into the cavity. When you insert the resin and the threaded stud, and then jiggle everything about, some of the resin oozes out to form a solid mushroom head inside the cavity - and that is not going to pull out, ever. 73 from Ian GM3SEK |
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Robin Szemeti - G1YFG
A friend of mine (G4JFB) rawl-bolted a "chimney mount" and full length of scaff pipe to his chimney .. with a 2m vertical, 70cm beam etc etc up the top. When the wind blew, it would wobble around dangerously. I always feared the rawl bolts would pull out one day, but, my fears were proven ill-founded as when the wind really blew hard one day the bolts held up just fine and we were able to examine them closely in his garden still firmly bolted to the bricks, along with the pole and most of the chimney ;) On Thu, 26 Jan 2023 at 15:35, Ian White <gm3sek@...> wrote: On Wed, Jan 25, 2023 at 08:57 PM, ian hope (2E0IJH) wrote: --
Robin Szemeti - G1YFG |
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The industry standard, for the mobile phone industry has been chemical fix anchor for many years. It's that way for a reason . Reg G8VHI -------- Original message -------- From: Ian White <gm3sek@...> Date: 26/01/2023 15:35 (GMT+00:00) To: UKMicrowaves@groups.io Subject: Re: [UKMicrowaves] Mast problem = UKAC no-show for DBN The old house down south was built with similar village-made bricks to Neil's, and dodgy mortar, so when mounting a Tennamast against the wall I asked them to make an extra-wide K bracket with a second crossbar below. That spread the load across a total of 7 fixing points at 3 levels, leaving clear courses of bricks between. I used resin anchors to avoid splitting the bricks; but they were rather new to the market back then. Even with well-cleaned holes, I still felt far from confident about the half-baked clay material itself. A useful tip from the Fischer Fixings literature was to drill clear through the bricks into the cavity, and then use the plastic mesh 'test tubes' to line the holes. These tubes are about an inch longer than the depth of the brick, with a closed end that overhangs into the cavity. When you insert the resin and the threaded stud, and then jiggle everything about, some of the resin oozes out to form a solid mushroom head inside the cavity - and that is not going to pull out, ever. 73 from Ian GM3SEK |
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Was your friend a member of the RSGB ? Radcomic is usually littered with diagrams illustrating many interesting and innovative ways to put excess sideways loading on chimneys. |
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Mike Willis
Opposite problem in the house up North. Local Bolton Bricks are so hard they tend to wear out the drill. Just as well though because on Winter Hill, the wind blows very efficiently. Rawl bolts, M10, M12, M14, as appropriate, but proper ones, not cheap copies, won't come out, but it is equally important to have plenty of mass above the upper fixing as the wall will give way well before the bolt shears.
-- Mike G0MJW |
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