Thanks: 0
Needs Pictures: 0
Picture(s) thanks: 0
Results 1 to 15 of 16
Thread: How to turn discs?
-
19th July 2013, 12:36 PM #1SENIOR MEMBER
- Join Date
- Oct 2008
- Location
- Syndey
- Age
- 38
- Posts
- 788
How to turn discs?
Ok, so there is probably a simple technique I am missing here, but I cannot figure out how to turn a disc which is rounded on both sides.
Example of what I am talking about:
I can imagine the process for a clock version:
For the clock, I would personally:
- use a faceplate with very short screws (into what will be the back)
- turn the front
- drill a hole with forstner bit for the clock face
- sand & polish etc
- then turn around and hold it in a chuck in expansion mode in the clock hole, and turn, sand & polish the rear side.
- then cut the base off using a mitre saw / band saw etc, so that it sits flat.
Is there something fundamental I am missing, because this process would not work for the disc vase shown above.
Holding the entire job in cole jaws seems out of the question, because of the curve in the shape (I have some of these at home, and from memory the centre is about 5cm thick while the very edges might only be about 1cm thick).
Thanks in advance, Simon.
-
19th July 2013 12:36 PM # ADSGoogle Adsense Advertisement
- Join Date
- Always
- Location
- Advertising world
- Age
- 2010
- Posts
- Many
-
19th July 2013, 02:19 PM #2GOLD MEMBER
- Join Date
- Sep 2008
- Location
- North Carolina, USA
- Posts
- 2,327
For the disk vase I would.
Put a round disk in my chuck with sandpaper glued on the face.
Jam the blank centered between the disk and a ring live center with a point.
Make a spigot for the chuck to grab and turn, sand, and finish all but the spigot.
Turn around and grab the spigot in the chuck, turn, sand, and finish everything I can reach front and back.
Remove from chuck and make a spigot or recess in a piece of scrap, put that in chuck and make a hollow area so that the edge will bear on the oval piece about 1/2 to 2/3 the diameter of the oval piece. Sand the front of the fixture smooth and drape a couple layers of soft cloth over it.
Place the oval piece against the fixture and gently bring up the live center in the mark left in the center of the spigot. Pull out the cloth so there are no folds. Tighten the tailstock firmly.
Turn off all the spigot you can reach, sand, and finish.
Remove piece from lathe, place on folded up towel, chisel off nub, hand sand, and finish. Drill hole, cut off bottom, sand and finish.
A two inch disk on a soft pad run by an electric drill works nicely for taking down the nub. When you are almost down to the surrounding surface, a two inch disk on a firm backing - cardboard - round and round, back and forth, rotating the piece, blends nicely.
See photos for removing nub from bowl bottom.So much timber, so little time.
Paul
-
19th July 2013, 05:49 PM #3Deceased
- Join Date
- Jun 2003
- Location
- ...
- Posts
- 7,955
Simon, for reverse chucking of that kind of shape I use the V grip extensions for the cole jaws from Vermec.
Peter.
-
19th July 2013, 07:30 PM #4
-
19th July 2013, 10:31 PM #5
I would turn down or glue a dovetail spigot on one side to hold with standard chuck jaws and then finish as much as possible of both sides from the one mounting. To remove the spigot, I know not everyone has one but it would be sooooo very easy on the vacuum chuck
-
19th July 2013, 10:42 PM #6SENIOR MEMBER
- Join Date
- Oct 2008
- Location
- Syndey
- Age
- 38
- Posts
- 788
-
20th July 2013, 01:03 AM #7
Hey Bassman
Maybe something in this thread will help with DIY cheaper option.
https://www.woodworkforums.com/f8/bow...nsions-172225/
Cheers Ben
-
20th July 2013, 03:22 AM #8GOLD MEMBER
- Join Date
- Sep 2008
- Location
- North Carolina, USA
- Posts
- 2,327
Simon, I looked for and couldn't find or open the above.
A lot of expensive stuff can be built by having a catalog page and a trip to a hardware store. combing the aisles and / or asking, "do you have something like this", will often get the same thing made from a handful of unrelated bits, and a few hours of work at much less cost.
Any round bits can be turned and drilled on the lathe.
Edit: Wrote this before reading #7 above.So much timber, so little time.
Paul
-
20th July 2013, 06:57 AM #9
If you are using flat boards near the thickness of the finished piece I prefer to use two temporary glue on chuck spigots (tenons) using hot melt glue. Requires two chuck & jaw sets plus a reversing mandrel though.
1. Glue on 1st tennon block one side & turn & finish the other.
2. Using a reversing mandrel and chuck position & glue on the 2nd glue block tennon to the finished side.
3. Reverse and use a "burn wire" to slice through the hot melt glue joint to recover the first glue block. I prefer to leave on the 1st & use it with tail stock support for as long as I can before removing.
4. Turn & finish the other side.
5. Part through 2nd waste block & remove remaining hot melt glue. It usually peels away easily from a finished surface.
I often use two glue blocks face to face - one in a nice hard material has the tennon, the other is softer and is a sacrificial waste block to be parted through. Another option is discs in aluminium machined with a tenon to suit your jawsets. Placing on an old electric clothes iron & heat will loosen the glue joint for removal.
If you are doing production runs TTIT's vacuum chuck is the only way to go. Be very very wary of techniques that some use to friction hold using tailstock force only to hold between jamb mandrels in the head & tailstocks or against the chuck jaw faces. One good catch or the tailstock working loose ever so slightly turns your piece into a flying discus.
ps there are various qualities in hot melt glue sticks. I prefer the Bostik glue sticks.
-
20th July 2013, 07:35 AM #10SENIOR MEMBER
- Join Date
- Oct 2008
- Location
- Syndey
- Age
- 38
- Posts
- 788
-
20th July 2013, 02:25 PM #11Deceased
- Join Date
- Jun 2003
- Location
- ...
- Posts
- 7,955
They are indeed perfect for the job of holding odd size items, such as disks or bowls or boxes with fancy edging, and IMO the only safe way to secure them to finish the bottom as it uses the cole jaws in compression mode. It is also very quick and easy to use. All other methods described seem as make do and have inherent safety issues.
I'll admit that they are a tad expensive but what price do you put on safety? They are a damn sight cheaper then doctors and hospital costs if the make do method holding it fails and the disk flies into your face.
Peter.
-
20th July 2013, 03:33 PM #12GOLD MEMBER
- Join Date
- Oct 2007
- Location
- vic clayton
- Posts
- 1,042
heres carl jacobsens way Woodturning Projects small vase on the lathe in two parts - YouTube
Some people are like slinkies - not really good for anything, but they
bring a smile to your face when pushed down the stairs .
-
20th July 2013, 05:04 PM #13
-
20th July 2013, 05:48 PM #14GOLD MEMBER
- Join Date
- Jun 2006
- Location
- Burwood NSW
- Age
- 82
- Posts
- 1,247
I have made them as TTIT describes using a vacuum chuck but have also done it by glueing on a tennon with titebond, then truing up the blank and finishing off the first face. I then hotmelt glue on a tennon to the finished face using the live centre to align it. Turn the job over and shape the other face and remove the glued on tennon using tailstock support as long as possible.I then zap it in the microwave oven to remove the hotmelt glue tennon and clean off any residual glue wih turps.
Ted
-
20th July 2013, 05:55 PM #15SENIOR MEMBER
- Join Date
- Oct 2008
- Location
- Syndey
- Age
- 38
- Posts
- 788
Similar Threads
-
Which Cutting discs?
By distractor in forum WELDINGReplies: 15Last Post: 17th September 2010, 07:53 PM -
150 mm sanding discs???
By Gramps in forum WOODWORK - GENERALReplies: 9Last Post: 30th September 2006, 09:59 PM -
Sanding discs
By Tools in forum WOODWORK - GENERALReplies: 1Last Post: 24th February 2006, 07:34 PM -
sanding discs
By Tonyz in forum FESTOOL FORUMReplies: 8Last Post: 25th October 2005, 02:53 PM -
Printer for discs
By journeyman Mick in forum NOTHING AT ALL TO DO WITH WOODWORKReplies: 5Last Post: 11th December 2004, 01:26 PM