Cutting a hole in ferro-cement

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bg9208

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I am considering buying a Hartley Tahitian. Looks like a good deal but it has a chemical toilet. As I would really need a marine toilet and holding tank I would need to cut one or two holes below the waterline. How does one do that? I could probably get through the cement by drilling a ring of small holes with a masonry drill(s) but how would I cut the armature if necessary?
 
bg9208 said:
I am considering buying a Hartley Tahitian. Looks like a good deal but it has a chemical toilet. As I would really need a marine toilet and holding tank I would need to cut one or two holes below the waterline. How does one do that? I could probably get through the cement by drilling a ring of small holes with a masonry drill(s) but how would I cut the armature if necessary?
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+ sealing the Armature after :eek:
 
Stitch drilling will probably work OK, but a diamond tipped hole saw will give a better result. You can hire the machine but will have to buy the blade.
A tip learned from a friends experience, dont use percussion or hammer drilling. This can cause "eggshell cracking" to surrounding areas. The armature can be cut with nips or hacksaw, as long as you avoid the frames.
 
A dry diamond core drill will cut it easy, it will slow it up a bit when cutting through the armature but it will cut through all of it.
I have done it many times when cutting holes for flues & drain pipes
 
DanTribe said:
Stitch drilling will probably work OK, but a diamond tipped hole saw will give a better result. You can hire the machine but will have to buy the blade.
A tip learned from a friends experience, dont use percussion or hammer drilling. This can cause "eggshell cracking" to surrounding areas. The armature can be cut with nips or hacksaw, as long as you avoid the frames.
Click to expand...

Diamond core drill are designed to be run slow in a conventional drill with a continual supply of water to lube & cool the drill core
 
I use diamond core bits regularly for drilling boiler flues and other holes in walls these are designed to be run dry but you certainly need a sds drill designed for core drilling as the torque needed will soon kill a conventional drill
 
I too am a plumber & use a dry diamond core drill for flue holes amongst other things. Note the word dry, they are designed to work this way & using an ordinary drill without a proper clutch may result in a broken wrist should the drill snatch whilst drilling.
 
Bert Large said:
I too am a plumber & use a dry diamond core drill for flue holes amongst other things. Note the word dry, they are designed to work this way & using an ordinary drill without a proper clutch may result in a broken wrist should the drill snatch whilst drilling.
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the OP has steel reinforcing to drill through so cooling essential imho
 
sailorman said:
the OP has steel reinforcing to drill through so cooling essential imho
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As previously stated, these drills are specifically designed to cut dry. If you had ever tried to drill a very damp wall with one you would find out why, they will barely cut with any moisture as it inhibits the exposure of fresh diamonds on the cutting edges.
Whilst not really designed to cut steel they will cut through reinforcing rods quite easily when dry as the amount of steel being cut is small compared to concrete area.
I have cut several 117mm dia holes in reinforced concrete lintels & whilst not quite the proverbial hot knife through butter it is a lot easier than some imagine with the right equipment.
 
Bert Large said:
As previously stated, these drills are specifically designed to cut dry. If you had ever tried to drill a very damp wall with one you would find out why, they will barely cut with any moisture as it inhibits the exposure of fresh diamonds on the cutting edges.
Whilst not really designed to cut steel they will cut through reinforcing rods quite easily when dry as the amount of steel being cut is small compared to concrete area.
I have cut several 117mm dia holes in reinforced concrete lintels & whilst not quite the proverbial hot knife through butter it is a lot easier than some imagine with the right equipment.
Click to expand...


+1
 
Re the Tahitian being a 'good deal' - please proceed very cautiously here!
Have you researched ferro-cement boats re their pros and cons? There are many threads on this forum about the subject.
To me, a 'good deal' on a ferro-cement boat might be one where I am paying just for the perceived (not new) value of the outfit items, ie I am getting the hull and interior free.
Especially as the cost of all second hand boats appear to have come down a lot in recent years.

There are a few good books on the subject - do a search on www.amazon.co.uk for 'ferro cement boat' and they will come up.

I have a copy of 'How to build a ferro-cement boat' by John Samson which explains things fairly well.
And there is a massive tome on the subject by Bruce Bingham, but copies of this are selling for gold dust on Amazon - between GBP 55 - 190 !!
I lusted after and could have bought one new 25 years ago for about GBP 20 (I had dreams then of building a ferro boat), but I couldnt justify / afford it then.
Just as well perhaps! :)

If you would like to read about the trials and tribulations of looking after a ferro cement boat, have a look at www.el-lobo.co.uk, and click on Mike's Maintenance page for the latest updates.
 
bg9208 said:
I am considering buying a Hartley Tahitian.
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Did you check with Hartley that it's one of theirs ? I enquired whether they could give me any info on a Tahitian I was looking at and got the reply "Although it has many aspects copied from our designs it is not one of ours".

I have to say that modified ferro designs worry me, 'cos just about anyone can knock a ferro boat up and you just don't know how well the design will work.

Good luck,

Boo2
 
Bert Large said:
As previously stated, these drills are specifically designed to cut dry. If you had ever tried to drill a very damp wall with one you would find out why, they will barely cut with any moisture as it inhibits the exposure of fresh diamonds on the cutting edges.
Whilst not really designed to cut steel they will cut through reinforcing rods quite easily when dry as the amount of steel being cut is small compared to concrete area.
I have cut several 117mm dia holes in reinforced concrete lintels & whilst not quite the proverbial hot knife through butter it is a lot easier than some imagine with the right equipment.
Click to expand...

i regularly hire-in a Diamond Drilling Contractor Guess wot he uses day in day out :p
 
Used to be able to hire diamond core and sds drill kit from Jewsons. I did it to cut hole for vent through house wall a few years ago. I don't think it cost much.
 
mikefleetwood said:
Used to be able to hire diamond core and sds drill kit from Jewsons. I did it to cut hole for vent through house wall a few years ago. I don't think it cost much.
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I hired one from HSS for a similar job. Their list price was quite high, but the guy in the shop spent a while applying every discount and exemption the till would let him, to get it down to what he considered reasonable.

Pete
 
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