ALL I wanted originally --was a tip on how to sand smooth a ebony goblet (foto posted )
see the nasty rings that persist ? How to avoid this ? tried every tungsten /scraper /sandpaper .emery cloth I can find --still those "RINGS " persist !
Surely there must be a solution ????
Attachment 453796Attachment 453796Attachment 453796Quote:
Originally Posted by ACACIA2
Oops sorry --only wanted one foto ----
blow up the image --u will see the lp record grooves that persist -on the lower trumpet base flange --
tried everything --even garnet & diamond /broken glass ---wire wool etc --i give up--
must be smooth like those tanzanian makonde carvings ---or maybe my diy homemade lathe is too slow ?2000 rpm max ?
Not trying to be smart here but....
Abrasives, glass, tungsten, scrapers, etc won't help, only good woodturning technique and sharp tools used correctly will clean up those nasty rings by not making them there in the first place.
Ebony isn't an easy timber to turn unless you have good turning skills. Those groves could be sanded out in a soft timber but not in ebony. However with good turning technique they wouldn't be there in softwood or ebony, so shouldn't need to be sanded out.
I'm sure others will agree and may give you some tips. The best tip I can give you to fix the problem is to get some lessons from a skilled turner. Maybe have a look on line and see if you can pick up some insight into turning goblets with clean smooth cuts.
Doesn't help with what you have right now unless you can re chuck and turn the inside again but might be of help for future goblets and other hollow objects.
Cheers - Neil :U
Have you tried hand sanding with the grain? Across the grooves? Fiddly, I know, but normally works for me.
Grooved or not, I love what you've done with this.
Your ebony is the next best thing to stone. Might as well call it stone, OK?
I carve some Brazilian steatite soapstone. I can carve it with a screwdriver if I had to.
Like finishing an automotive paint job, the final surface gets 400 then 600 then 800 then 1,500 grit 3M Wet and dry sandpaper, used wet.
I wet the stone and rub the papers into that.
Then it has to really dry for a final waxing and buffing with a lot to friction to heat the wax.
What I get is a water-wet, glossy looking surface with no scratches.
Of course, you can leave parts at any stage for a different surface appearance.
Have you tried a Negative Rake Scraper on a 45° angle? That's what I use and with care it takes microscopic fluffy shavings off.Quote:
Originally Posted by ACACIA2
Rgds,
Crocy.
That's a good looking vase, Acacia2. I can see why you want to remove the rings. Near the flare just below the stem, are those sanding lines or are they growth rings?
Now to your question. If the piece can be remounted, and the opening is large enough to use a small powered sanding disc in it, start with 60 grit, and sand until the grooves disappear. Go through the grits up to the finest made, 220 grit here in the U.S. After the finest disc, then hand sand with the other fine grits until you are satisfied. ............. Jerry (in Tucson)USA
REALLY APPRECIATE YOUR COMPLIMENTS --I AM BLOWN AWAY BY YOUR GREAT ADVICE ---MANY THANKS TO ALLQuote:
Originally Posted by Nubsnstubs
( no -those rings you see on base flare are not growth rings ----nasty grooves that wont go away !!
Takes a fair bit to get me to post in here and it's usually because peope don't get the gist of a question. So, sorry if I rain on anyone's parade but it looks like almost everyone completely missed the point of this thread with the exception of ubeaut and Old Croc.
It's ebony people sanding won't help in most instances it will just blunt the abrasive. Those rings need to be scraped or clean cut out before sanding. The lines at base of goblet are testament to what abrasive will/won't do.
Ebony is usually unforgivable when it comes to turning and finishing so as mentioned above sharp tools and clean precise cutting is imperative as flaws usually can't be sanded out like you can with softer timbers.
Darky
Ubeaut is on the money! Especially for hardwoods sanding only takes away such a small amount each grit. Freshly sharpen will get you there plus technique, though I have none of that!!!
me 3 brainstrust. Technique, isn't that a French dance/night club?Quote:
Originally Posted by brainstrust
Neil & Crocy are on the money, however I disagree on a minor point - correct sanding technique can take out some / most / all of the flaws (if there is sufficient wall thickness of course). Unfortunately to many turners are in a rush to complete a project and do not think ahead far enough to make life easier for themselves in the following tasks.
Aggressive roughing cuts often lead to multiple problems later on, so as both Neil and Crocy say only good turning techniques will solve those issues. Many of the harder timbers such as Ebony, our Australian Gidgee's etc, respond far better to dare I say it "scraping" in the finishing cuts. A good scraper used in "sheer scraping" mode can remove what many turners refer to as "angel hair" shavings on those woods, so fine that they seem to hover or float in the air. That will reduce a lot of sanding effort!
A significant issue with sanding extremely hard woods is lathe speed - most turners sand way to fast at high lathe RPM's which then generates lots of heat, causes end grain checking, often creates burnishing, brings resins etc to the surface, wears out sandpaper very very rapidly, and produces a pretty poor sanding result!
Slow the lathe speed right down to 300rpm or so, start to sand with a grit coarse enough (perhaps #100 to 120 maybe #80) to remove the material in those unsightly rings. As sanding progress slows throw the paper and resume with a fresh piece of the same grit. If progress is to slow go down another grit! ONLY when the rings are removed down to the desired surface, go up to the next grit, then sand until any sanding groves are removed. Repeat progressively going up the grits until at least 1200# on ebony etc. Don't be tempted to skip grits on very hard woods!!!! Then use some of Neil's fantastic EEE at his recommended lathe speeds and you should end up with a finish that most turners would be very proud of. That should be "good enough" for ebony as it will retain a high lustre with no other finishing required.
Wet sanding can also be very useful on very hard woods, with a "cutting fluid" such as water, mineral oil etc used as both a cooling medium and as a lubricant. Wet sanding will also fill pores, and requires that a wet slurry be maintained at all times while sanding. One can easily tell when the slurry dries as the paper gets "grabby." Wet the paper again with your chosen "cutting fluid" and resume. Finishes such as Organ Oil's "Hi-Speed Finishing Oil" ( or "Hard Burnishing Oil") are designed to be used in that manner - Organoil
Thankyou Darklord ---appears you understand just how difficult ebony types can be --this is combretum imberbe -
can be a real sod to achieve a smooth finish ---appreciate the advice --
will re-sharpen diy tools & start all over ----using WET deadwood this time ---that dry ebony is glass hard --always those lp record ugly lines appear -----and I never get this with a dozen other Zulu hardwoods ----just Imberbe !
Many thanks to all who gave me great advice -have now more determination to clean up this unsightly mess
ACACIA2
most grateful to Mobyturns ----
this combretum is huge & heavy --my diy lathe slowest speed is 250 rpm --fastest is 2000 rpm
got to start roughing VERY slow ---or the ebony mass will tear itself out of the faceplate (deeply imbedded self tapping screws
can sheer off ---especially with 40 -50 kg mass of crooked ebony log whirling /vibrating /shaking like hell !
scary to rough it esp the dry brittle variety ---like concrete !!
I will rather use wet cut combretum now --turns easier ----better results ---
thankyou for the insight & great ideas -----
ACACIA2