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Under cutting a hollow form.

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sue denim

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I have had lots of fun / experience on the lathe and I am taking things to a new level. I now have more time and a huge workshop to play in.
I would like to crack one area that has eluded me since I started turning. I think the problem lies in the fact that I don't have the correct tooling. The area in question is the underside of the roof if you see what I mean.

I want to be able to hollow out 'sea urchin' shape forms.

The only tools that I have regards bowl turning are a 'long and strong' bowl gouge and a scraper with an offset tip.

If I am going to part with some beer tokens then which tool do you think may suffice ?

I think I will need a free standing tool rest as the Myford integral rest is just too close to the head stock and restricts the diameter of the work piece.

Please let me have your experiences good and bad so that I may make an informed choice.

Just for the fun here's the latest effort.

Regards 'Sue'
resize bowl.jpg
 

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CHJ

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Simon, if you have no dedicated hollowing tools then I would venture that your best bet, although you might need a good one to raise the cash, is the Rolly Munro Hollowing Tool.
 

drillbit

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If the rolly munroe is prohibitively expensive, you could do worse than the crown cryo which seems to be the pot mans version. I have had some success with it, and since I am very inexperienced, the tool must be doing most of the work.
 

Elaine

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try this link http://www.marksanger.co.uk/revolution% ... ystem.html
i asked about the comparison between this and the rolly (which I have) the crown tool looks more versatile, and it is on offer at the moment. all about choice really and getting to grips with whichever one you go for. the more I use the rolly munro the easier it is.
 

hughie

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Theres a few ways to make your own, it depends on your ability and tools to hand. The first pic is a fairly elaborate one that requires bending and welding.
The second is a Oland type tool with an offset piece of HSS 6mm sq. The holder is 20mm dia with the hole drilled at around 40-45' or so and held in place by a m6 grub screw. Much simpler, very easy to make and highly effective.
 

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mark sanger

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Hi

It is no secret that I sell the Crown Revolution so I will clarify this now as an interest.

There is no " best" hollowing tool" on the market as it is work specific.

If you want to hollow unseasoned end grain work then a ring type cutter will be the best option as this is what they are designed fo,r and come in many designs. You can also hollow seasoned end grain and cross grain with them but depending upon the wood, density etc it may not be the best option and due to the radius/size of the cutter there can be a larger surface area in contact with the wood, which on seasoned wood can make it harder to hollow at depth.

If you want to hollow seasoned cross grain particularly a dense wood or alternative material then a small scraping tip is the best tool as there is reduced stress on the tip due to a smaller cutting area ( which reduces forces and difficulty of use), also chip formation is different for dense dry cross grain wood than it is for green end grain and it chips better that it does peal so a scraping tip is a better option but not always a given.

If you want to hollow forms through a small hole with a steep undercut you will need a system that allows you to crank the head so that you can reach the areas you want.

You will need to crank in two locations so that the cutting tip can be kept in line with the shaft of the tool as much as possible. If there is only one link then the further the cutting tip is angled over the more difficult the control of the tool will be.

So if you want a versatile tool that will enable you to tackle a lot of different hollowing processes then you need versatility, ring cutters scraping tips, finishing scraping tips etc. Some tools come with these and some cheaper ones don't come with them as standard and you have to pay extra to get the extra bit to make the tool versatile enough to work with if your hollowing is not specific. So they are then not as cheap or as versatile as they initially are advertise, the devil is in the detail.

So what ever hollowing system you purchase I would advise that it is a versatile one as sometimes is it worth spending a bit more for a lot more than saving and then having to buy extra bits or another tool later.
 

sue denim

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Today I weakened and splashed out on a revolution 5/8 tool.

I will let you all know how I get on with it.

Watch this space

'Sue'
 

jumps

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do share your experiences Simon - I still think this thread should be in the equipement stickies.....Mark's post is priceless.
 

sue denim

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OK so I bought one.
Ordered Thursday and arrived the following Tuesday, that was on the economy postage.
I am impressed with the overall build of the tool and it has some weight to it. It feels 'heavy duty'.

I didn't get a chance to use it until today as the Wife wanted me to turn the barn next door into an art gallery :roll: .

First thing I did with the tool is finish a 150mm tall vase that I made ages ago but couldn't hollow due to the depth etc.
Lesson number one is this.....don't start out with and end grain 'dry as dust' oak vase .

It did the job but I felt it was a bit of a struggle. It removed the wood really quickly. I think the struggle was down to never having used an undercutting tool and the 'hard as iron' oak.

The next thing was a pot pourri bowl . This was in a spalted wood (sycamore I think) . This was a completely different experience. With the ring cutter I could control the cut and could really feel what was going on at the business end. Took the wood out very quickly (almost too quick !). I got the occasional 'pull in' but I think this is down to me being heavy handed.

All in all worth the money, as I am sure are the others on the market. Shame I haven't enough money / time to try them all.

Regards 'Sue'

Thoroughly pleased with it and looking forward to trying it out on other items.
 
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