On 24/09/2023 15:39, John Rumm wrote:

> ...anything can cut battens to length, and thin ply.

Then perhaps it's just me but I certainly can't produce accurate cuts
across battens or dead straight lines in sheet material, at least not to
match machine tools. I no longer have a chop saw and I've never owned a
table saw, alas.

Bert

On 24/09/2023 15:37, Robert wrote:

> However I am sure they are designed to be stood on solid
> surfaces so airflow should not be an issue.

You're quite right about the solid surface underneath the unit but air
circulation around and above it can be critical.

Bert

Bert Coules <mail@bertcoules.co.uk> wrote:
> On 24/09/2023 16:40, Tim+ wrote:
>
>> Serious question, is weight really an issue?
> You must not have seen my previous answer to that: when you're working
> on your own and have to hold something up to the ceiling while
> simultaneously securing it to the joists, weight is most definitely an
> issue.
>
> Bert
>

No one handy who can help?

Tim

--
Please don't feed the trolls

On 24/09/2023 16:56, Bert Coules wrote:
> On 24/09/2023 15:39, John Rumm wrote:
>
>> ...anything can cut battens to length, and thin ply.
>
> Then perhaps it's just me but I certainly can't produce accurate cuts
> across battens or dead straight lines in sheet material, at least not to
> match machine tools.  I no longer have a chop saw and I've never owned a
> table saw, alas.

Well there are still ways to improve your accuracy. A quick and easy one
would be to get (or make) a simple mitre box - basically a U channel of
wood with reference cuts in it to guide your saw.

Another technique is the knife wall method. Marking out your cut using a
knife rather than a pencil, then using a chisel to pare relief cuts into
the waste part of the wood. This creates a very nice "step" you can saw
against. Easier to see it done than describe:

https://www.youtube.com/watch?v=9iQ1-kuQ1qY

The other option is to make a shooting board:

https://www.youtube.com/watch?v=-Ypbvcxb-8M

Basically you rough cut a bit longer than actually required, then plane
the end flat and square exactly to your desired length.

--
Cheers,

John.

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On 24/09/2023 16:53, Bert Coules wrote:
> On 24/09/2023 16:40, Tim+ wrote:
>
>> Serious question, is weight really an issue?
> You must not have seen my previous answer to that: when you're working
> on your own and have to hold something up to the ceiling while
> simultaneously securing it to the joists, weight is most definitely an
> issue.

Yup, but sometimes simple stuff like a length of rope to hold a free end
of something, or a dead man prop[1] can help. Also a board across a
couple of step ladders as a temporary staging etc.

Also building stuff so that you can fix a light part, and then hook the
heavy bit on after while fixing.

[1] https://wiki.diyfaq.org.uk/index.php/Dead_man_prop

--
Cheers,

John.

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John, thanks for the link and the earlier advice. Over the years I've
cobbled together many and various gizmos to compensate for my solitary
DIY efforts, most of them at least moderately if temporarily successful,
even if I do say so myself.

But when it comes to accurately cutting and shaping, though I've tried
almost every hint, tip, and helping aide known to man, I still remain a
disgrace to the DIY world.

On 24/09/2023 14:10, John Rumm wrote:

> M12 threaded rod from an electrical wholesaler is very cost effective > source IME:
Thanks for those links, John. Whatever size I end up using I wish I
could remember how I attached the bottom shelf in the earlier version
with nothing visible on the underside. I suppose I could have used a
nut, perhaps with a washer, rebated into the MDF or whatever it was, and
then filled the hole flush, but the board looks too thin for that.

On 24/09/2023 19:34, Bert Coules wrote:
> On 24/09/2023 14:10, John Rumm wrote:
>
>> M12 threaded rod from an electrical wholesaler is very cost effective
>> > source IME:
> Thanks for those links, John.  Whatever size I end up using I wish I
> could remember how I attached the bottom shelf in the earlier version
> with nothing visible on the underside.  I suppose I could have used a
> nut, perhaps with a washer, rebated into the MDF or whatever it was, and
> then filled the hole flush, but the board looks too thin for that.

Counter bored to allow the nut to be hidden sounds like a good option.
Also you can actually tap a thread into MDF and screw your threaded rod
straight in. The thread will be quite strong since you are not
repeatedly undoing and remaking the join.

--
Cheers,

John.

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On 24/09/2023 19:41, John Rumm wrote:

> Also you can actually tap a thread into MDF and screw your threaded rod > straight in. The thread will be quite strong since you are not >
repeatedly undoing and remaking the join.
Not that I doubt you about the strength, but I don't think I'm in a
hurry to entrust my projector to four screw threads tapped into MDF.
Sinking the nuts into the shelf and filling the holes sounds good. Thanks.

On 24/09/2023 19:34, Bert Coules wrote:
> On 24/09/2023 14:10, John Rumm wrote:
>
>> M12 threaded rod from an electrical wholesaler is very cost effective
>> > source IME:
> Thanks for those links, John.  Whatever size I end up using I wish I
> could remember how I attached the bottom shelf in the earlier version
> with nothing visible on the underside.  I suppose I could have used a
> nut, perhaps with a washer, rebated into the MDF or whatever it was, and
> then filled the hole flush, but the board looks too thin for that.
>

I have in the past used flanges which screw onto wood, board etc and
take bolts or threaded rod like

https://www.amazon.co.uk/sourcing-map-M12x40x2-5mm-Carbon-Screw/dp/B07H5BKDMF

--
Robin
reply-to address is (intended to be) valid

On 24/09/2023 20:34, Bert Coules wrote:
> On 24/09/2023 19:41, John Rumm wrote:
>
>> Also you can actually tap a thread into MDF and screw your threaded
>> rod  > straight in. The thread will be quite strong since you are not >
> repeatedly undoing and remaking the join.
> Not that I doubt you about the strength, but I don't think I'm in a
> hurry to entrust my projector to four screw threads tapped into MDF.
> Sinking the nuts into the shelf and filling the holes sounds good.  Thanks.

I think I would be tempted to use a proper mount, since they give plenty
of control of azimuth, elevation and yaw, which can make alignment much
easier. They are also designed for easier installation since you can
normally fix the main ceiling mount bit before adding the heavy bits.

--
Cheers,

John.

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On 24/09/2023 21:36, Robin wrote:

> I have in the past used flanges which screw onto wood, board etc and > take bolts or threaded rod like> >
https://www.amazon.co.uk/sourcing-map-M12x40x2-5mm-Carbon-Screw/dp/B07H5BKDMF
I didn't know about those; thanks. If I do use them I think I'd drill
holes right through the shelf and insert the fittings from underneath.
It would maximise the support, and the relatively thin flange could
easily be sunk into the MDF/timber/whatever.

Bert

On 24/09/2023 22:21, John Rumm wrote:

> I think I would be tempted to use a proper mount...
I've used them in the past and I recognise the advantages but I just
don't like the appearance of them I'm afraid. A suspended shelf can
look like a built-in feature (however unlikely) which just happens to
have had something plonked on to it; a single-column mount looks like
nothing on earth. But thanks for the thought.

On 24/09/2023 15:37, Robert wrote:
> On 24/09/2023 15:18, Bert Coules wrote:
>> On 24/09/2023 13:54, John Rumm wrote:
>>
>>> Or a basic torsion box design...
>> That would certainly solve any possible rigidity problems but I do
>> like the open plan look of my previous effort.  And ventilation, or
>> the lack of it, would be troublesome: those projectors generate a fair
>> bit of heat and need a good air flow around them.
>>
> Drill some largish holes through the torsion box underneath the air
> grills. However I am sure they are designed to be stood on solid
> surfaces so airflow should not be an issue

Adding longer feet to the equipment to raise it further above a solid
surface can add to the airflow. I would guess that something that
potentially gets very hot would have forced air cooling via a fan.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 24/09/2023 22:45, Bert Coules wrote:
> On 24/09/2023 22:21, John Rumm wrote:
>
>> I think I would be tempted to use a proper mount...
> I've used them in the past and I recognise the advantages but I just
> don't like the appearance of them I'm afraid.  A suspended shelf can
> look like a built-in feature (however unlikely) which just happens to
> have had something plonked on to it; a single-column mount looks like
> nothing on earth.  But thanks for the thought.

They are not all single column... many fit flat to the ceiling (I have a
list of probably 300 from my supplier of AV kit)

But yup I take your point, you might as well go for works best for you
visually.

--
Cheers,

John.

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On 24/09/2023 16:58, Bert Coules wrote:
> On 24/09/2023 15:37, Robert wrote:
>
>> However I am sure they are designed to be stood on solid surfaces so
>> airflow should not be an issue.
>
> You're quite right about the solid surface underneath the unit but air
> circulation around and above it can be critical.
>
> Bert
>
I would expect the maker to provide recommended minimum clearance
dimensions for a Video projector which might be ceiling mounted,

On 25/09/2023 09:23, Robert wrote:

> I would expect the maker to provide recommended minimum clearance > dimensions for a Video projector which might be ceiling mounted.

And so they do, and so they did in this case, but in my experience, the
more clearance, the better.