DIY pushpit mods. Fitting and cutting please

[pcatterall]

Now we are doing more of this stern too mooring we want to alter our pushpit so we can walk through it rather than staggering up the gang plank and climbing over it.

I have worked out what to do and it seems that I can get tube and fittings from Sea Screw, a few questions arise.
I know that I can cut SS tube here at home using a thin disk in my 4“ angle grinder. I have not got a grinder on my boat ( in Italy) but understand that A hacksaw with 14 teeth per inch will cut 25mm 2mm wall tube OK, is this the case and are there any recommendations about where to buy suitable ( 12“) blades?
The Sea Screw fittings have little grub screws with points will these just grip the inner tube OK or is there advantage in making a little ‘counter sunk’ type hole for the screw point to ‘locate’ in?
I really need to fit a 20mm tube at right angles to a 25mm tube, there are lots of T type fittings for 25 and for 20 mm tube but I really need an ‘unequal T’ for the job, any ideas if I can locate one anywhere/ If not then hopefully I can fit the 20 mm tube into some 25mm and the 25mm to the T ?
Grateful as always for any input on this.

 

[Norman_E]

14TPI blades are too coarse for cutting quite thin walled tube. For hand hacksaw blades 18, 24 & 32TPI are the standard tooth pitches. I would use 24TPI or even the very fine 32TPI blades. What you want are the flexible bi metal blades which have hard high speed steel teeth and a flexible carbon steel back, like these http://www.ebay.co.uk/itm/5-x-ECLIP...t=UK_Hand_Tools_Equipment&hash=item4626257907 Eclipse blades are a good make.

Get a good quality hacksaw frame that can put a lot of tension on the blade, cheap and weak frames lead to broken blades and wavy cuts.

 

[earlybird]

Sound advice above. Also, for serious hacksawing, esp SS tube, a good vice is needed. Holding the work with one hand or a knee won't do.

 

[David2452]

For cutting thinwall SS tube perfectly square and quickly a decent tube cutter is a good tool. A Rothenberger number 50 will do nicely.

 

[PuffTheMagicDragon]

Of course, not knowin quite what you intend to do, I can only make general obsevations.

Why mix 20mm when your existing is 25mm? One can easily see the difference between 25mm and 1" and that is only 0.4mm; you are proposing a difference of 5mm.

A hacksaw blade with14tpi seems rather coarse to me; I would 80 for 24tpi if I couldn't source 32tpi. I would also go for professional quality HSS blades, not the cheap ones that are intended for DIY work.

If you are going to replace the top bar with an opening section I would consider leaving one inch on each side and cover the cut end with the type of end-fitting that is used on biminis. A length of flexible SS cable clips onto these fittings to close the opening, something along these lines:

Re the grubscrews, I prefer to replace them with SS bolts and Nylock nuts, passing then through holes drilled right through the fitting and the tube.


Apologies if all of this is irrelevant to your situation.

 

[planteater]

For cutting thinwall SS tube perfectly square and quickly a decent tube cutter is a good tool. A Rothenberger number 50 will do nicely.

Agreed. I bought a Ridgid 150 LS and it makes the job much easier. You can sell it on Ebay when you've finished and get most of the cost back!

 

[Concerto]

My Westerly Fulmar has a hinged bar with a wingnut screw fixing whilst sailing. You will use the centre section for the hinged bar so everything will match.



This photo shows the pushpit section open.

The fittings are stainless steel and could probably be tracked down through Trafalgar Yachts http://www.westerly-yachts.co.uk/.

 

[pcatterall]

Many thanks for the suggestions, I have ordered the suggested saw blades.

Thanks also for the 2 photos; I see that in both cases the the top bar has simply been cut out.
my pushpit is basically the same except that the gap between the two inner supports is much bigger at 1400mm, the top tube is 25mm but the lower tube is only 20mm. ( Hence the need for an unequal Tee)
My proposal involves cutting both tubes and fitting 2 more supports to the deck. I had considered just cutting the top bar and dropping two supports down to the lower bar but had concerns about the strength involved.
new tube and fittings seem to price out at just under £100 which is just managable for an OAP!!