G
Guest
Guest
We have a Golden Hind with a hole for trhe stern tube just over three feet long. We have to enlarge the diameter by 2-3mm to get the new stern tube in. Any ideas on how to do it?
Chris
Chris
vyv_cox
Well-known member
Now, that's a good one! Should attract some interesting posts.
It seems to me that you need some sort of expanding reamer but it needs to be centred on the existing hole. There will be an official tool for this but no doubt hard to find, impossible to hire and incredibly expensive.
I can only think that you use the existing stern tube, or another tube the same size, as the guide. Silver-solder two tool-steel cutters (use lathe or milling tools) to one end of the tube to the required new diameter. Fix a handle on the other end of the tube. Feed through so that the cutter comes through last, turn the handle and pull.
Good luck with this very challenging modification.
It seems to me that you need some sort of expanding reamer but it needs to be centred on the existing hole. There will be an official tool for this but no doubt hard to find, impossible to hire and incredibly expensive.
I can only think that you use the existing stern tube, or another tube the same size, as the guide. Silver-solder two tool-steel cutters (use lathe or milling tools) to one end of the tube to the required new diameter. Fix a handle on the other end of the tube. Feed through so that the cutter comes through last, turn the handle and pull.
Good luck with this very challenging modification.
G
Guest
Guest
Post deleted by danfoley
vyv_cox
Well-known member
3 ft long long drills at 2 inches or so diameter don't come cheap. And what would you drive it with? Better to use the existing hole as a guide and enlarge it.
tr7v8
Active member
Boatwrights use a travelling cutter on a long threaded rod, initially driven by hand and then by big leckie drill. Bl***y expensive and very specialist. Have a ring round specialist wooded boat builders I am sure someone will be able to do it.
I have got a piccy somewhere of this beast from somewhere like the www.duckworks mag or similar.
Jim
---------
I have got a piccy somewhere of this beast from somewhere like the www.duckworks mag or similar.
Jim
---------
tr7v8
Active member
'nother thought is if you found a piece of tube/rod about the right size and either heat it or sharpen the end, 3mm is 1/8th inch and is a ver small amount.
Jim
--------
Jim
--------
oldsaltoz
New member
G’day Chris.
Welcome to the forum, I’m sure you will get the right answer/s to your questions here and also get your post hijacked from to time.
I’m not familiar with the brand so am not sure if she is timber or fibreglass but would think you need to bore out over size and reline the new hole to protect the timber or glass then insert new tube.
Have a look for a line boring engineering firm, not cheap but accurate. The only other alternative would be a pull through shaft with cutters on the end.
I hope this helps.
Avagoodweekend Old Salt Oz……
Welcome to the forum, I’m sure you will get the right answer/s to your questions here and also get your post hijacked from to time.
I’m not familiar with the brand so am not sure if she is timber or fibreglass but would think you need to bore out over size and reline the new hole to protect the timber or glass then insert new tube.
Have a look for a line boring engineering firm, not cheap but accurate. The only other alternative would be a pull through shaft with cutters on the end.
I hope this helps.
Avagoodweekend Old Salt Oz……
Twister_Ken
Well-known member
I suppose getting a stern tube which is the same size as the old one is out of the question?
spark
Member
tr7v8 has the answer but it needn't be expensive. The yard where I served my time had a home-made one.
Threaded rod is available off the shelf in 2m lengths (if you can't find any get a machine shop to run one off for you).
Thread a cutter (wood: modify one from an expanding bit. f/glass: not so sure - maybe a HSS drill bit ground to shape?) and tap it into the rod at approx. half way.
Tap a couple of hefty steel plates to take the rod and set them up (one inboard one outboard fixed nice and rigid) centred. Set the cutter at the existing diameter to get the centre.
Only use a power drill if it can turn the rod at slow speed and has a decent side handle. If the drill runs too fast or you hit a hard spot (e.g. nail) it can take charge of you and do serious damage.
Safer (but slower and more sweat) to use a turning bar on the end of the rod. 1/8" should be fairly easy to scrape off.
Threaded rod is available off the shelf in 2m lengths (if you can't find any get a machine shop to run one off for you).
Thread a cutter (wood: modify one from an expanding bit. f/glass: not so sure - maybe a HSS drill bit ground to shape?) and tap it into the rod at approx. half way.
Tap a couple of hefty steel plates to take the rod and set them up (one inboard one outboard fixed nice and rigid) centred. Set the cutter at the existing diameter to get the centre.
Only use a power drill if it can turn the rod at slow speed and has a decent side handle. If the drill runs too fast or you hit a hard spot (e.g. nail) it can take charge of you and do serious damage.
Safer (but slower and more sweat) to use a turning bar on the end of the rod. 1/8" should be fairly easy to scrape off.
petery
New member
West epoxy have an interesting solution in their literature when you want to drill around an in-situ keel bolt to give an extra mm or so, down which you pour epoxy.
They suggest you braze a hole-saw blade onto a length of gas pipe and fit it around the existing keel bolt; drilling/cutting around it.
Perhaps you could adopt this idea by putting an undersize rod in the exisiting stern tube hole from the outside to centre the drill and then use their technique from the inside to drill an annular hole around it.
They suggest you braze a hole-saw blade onto a length of gas pipe and fit it around the existing keel bolt; drilling/cutting around it.
Perhaps you could adopt this idea by putting an undersize rod in the exisiting stern tube hole from the outside to centre the drill and then use their technique from the inside to drill an annular hole around it.
stamfordian
New member
Got a stern tube kit sorplus to requirements 1 1/4 inch bsp thread about 1" shaft,need your own tube threading ,Could you use same tube as old??.Picture below in link,And in for sale section for part no,s
http://www.arweb.co.uk/argallery/stamfordian
http://www.arweb.co.uk/argallery/stamfordian
Avocet
Well-known member
If you have access to brazing / welding gear you could try getting a 4 foot piece of tube (or solid bar) the same diameter as the existing hole. About a foot or so down from one end, braze or weld a couple of "fins". on it such that the width across the "fins" is the same as the diameter of the required hole. You could try making them out of something hard like an old file and brazing them on (even if you have to slot the tube to loose some of the thickness of the file blade). Then weld a spigot on the end of the main tube small enough in diameter to fit in the chuck of a powerful electric drill and ram the whole lot up its...
The first foot of tube will (hopefully) act as a guide to keep the whole lot concentric and the "fins" should do the cutting. They will probably go blunt after several inches so you might have to replace them several times before you get to the end but I think it should work.
Good luck!
The first foot of tube will (hopefully) act as a guide to keep the whole lot concentric and the "fins" should do the cutting. They will probably go blunt after several inches so you might have to replace them several times before you get to the end but I think it should work.
Good luck!