LaymarCrafts Woodturning Hints & Tips

Deep Boring System Pt III

The third and final part of this Article covers the various Tool Rests I have made to use with the Deep Boring System described in the previous two parts, and I conclude with a Height Gauge used to set the Tool Tip for Deep Boring.

As explained earlier in the article my preferred position for Deep Boring is with the Lathe Headstock rotated by 15 to the centre line of the Lathe Bed, this presented me with a problem for the Tool Rest as I felt that with any Rest I could end up with a Overhang that would not give adequate Tool Support, with even the possibility of Tool Rest/Banjo Failure.

My solution was to make a Tool Rest with a two point support, at one end of the Tool Rest I had a Pillar to suit the Banjo and at the other end I fix a Support Leg  exactly the same as that used for the Trap but longer.

As can be seen in the sketch above I started with a 50mm x 25mm [2" x 1"] Heavy Duty Steel Hollow Section in my case I made this 400mm [16"] long, although any reasonable length is possible.

At one end I drilled a clearance hole suitable for the screwed portion of a Tool Rest Pillar [mine came from Craft Supplies UK item SG205 which is the 20mm version to match the Banjo of my Lathe] I then found a Nut to match the Thread of the Pillar.

You may need to reduce the width, depending on the Size of the Nut, across two of the Flats but make sure you take equal amounts of each as it is preferable that the assembly is central, you will also need to contour the edges of these flats to allow for the radius in the corners of the Hollow Section.

In the sketch you will notice that I have placed a Washer between the top of the Pillar and the underside of the Rest this ensures the Undercut of the Threaded Portion does not protrude through the Hollow Section and prevent you from Tightening the whole assembly up.

Of course if you have the means you could simply Weld a suitable size Pillar to the Hollow Section making sure it is square in all directions.

At the other end I followed the same procedure only this time with a length of M12 ["] Screwed Rod to which you will attach the Support Leg detailed below.

As I made both the Pillar and Screwed Rod a permanent fitting I applied a few drops of Thread Lock to ensure that the assembly could not come loose at any time.

The Support Leg is constructed exactly the same as for the Trap described in Part II, except the Height will require adjusting to suit your particular set up, I used a 100mm [4"] long Set Bolt to give me ample adjustment with the Top of the Rest in any usable position. The Photo below shows the Rest with Support Leg in position.

The Rest can be used as shown or with the Banjo in it's more normal position for off center Turning, below is another option of Tool Rest I use for various forms of Turning including some Hollow Vessel Work.

For Hollowing with the Headstock in its normal position I made this T Bar Tool Rest from two pieces of 20mm Steel Bar welded together, by my local Blacksmith, it works well and does not appear to Flex when the Tool is being used towards either end.

The rest is 320mm [12"] long and I believe this could well be near to the maximum length for the diameter of Bar used, obviously the larger the diameter the longer you should be able to make the Cross Bar part of the Rest, but I started with 320mm and found this suited my needs and was always aware of the fact that if the overhang was too great and I was getting any Flexing I could trim it back or add some bracing.

The total cost for this rest including the Welding was less than 5 [$3.5] and the cost for the Larger Rest with the Support Leg was under 15 [$10.5] and this includes the Pillar which cost me 6 [$4.3].


Tool Tip Height Gauge

The Tool Tip of any Hollow/Deep Boring System once in the Vessel being Turned is out of sight, it is therefore that you set the Tool Rest Height Accurately if you are to achieve a Good Cut with No Dig Ins or Catches.

As I always Turn with the Tool Tip on the Centre Line I made a Fixed Height Gauge and soon found that should I need to Work with a setting below centre at any time it was easy to judge the correct amount using the Gauge.

I started with an off cut from the 1" Square Hollow Section used for making the Trap and cut this to a length that would straddle the Lathe Bed [Ways] in the centre of this I drilled a 9mm Hole into which I fitted a suitable length of M8 [3/8"] Screwed Rod which was then clamped in place with 2 suitable Nuts as shown above.

For the Gauge Height Indicator I used an M8 Penny Washer, but any suitable Plate or Disc will do, this again was clamped between two suitable Nuts.

You now need to set the Gauge, the underside of the Washer, to the Centre Height of the Lathe Spindle and lock the Washer in place with the two M8 Nuts.

A few drops of Thread Lock in all the right places will ensure the Gauge stays at the correct Height, the addition of a length of Plastic Hose over the threaded portion of the Gauge and a lick of Paint will finish the Job Off.

The picture above shows the Height Gauge in use with the Deep Boring System and the T Bar Rest, with this aid you can easily set the Cutter so that it cuts on the centre line of the Piece being Turned or below centre as required.

Part I of this Article.
Part II of this Article.



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