djaxon
starting to spend too much on rocks
Member since February 2015
Posts: 159
|
Post by djaxon on Jun 4, 2015 18:19:42 GMT -5
Just completed the 'rebuild' of my FranTom 10" Combo. It came with two installed grinding wheels and two spares. One of the installed wheels is labeled Lortone silicone carbide grinding wheel "Cascade". Max 4775 RPM, 6"x1"x1", LCG 100. The other wheel has no label but is obviously "smoother" than the 100. I plan to use these two wheels to get the feel of the grinder and to learn the basics (I hope). My questions: Can these wheels be dressed? If so, how? When I am ready to replace these wheels, do I go with Silicon Carbide or diamond wheels. I know that it's a matter of personal preference but am looking for your opinions and observations on the comparisons between CS and Diamond wheels. Hope to post some photos of the Combo soon. So far I have been pleased with this $150 purchase. Have only had to spend about $5 for a switch for the motor and will soon buy a replacement belt - probably link belts. Thanks for your input. dj
|
|
|
Post by mohs on Jun 4, 2015 20:03:19 GMT -5
Hi dj
I like S/C wheels They last a llooong time! and rough grind a dome very efficiently., Use real light pressure.
Dressing a S/C smooth is a task though. I have the hardest time with that. The wheels have a tendency go out of round quickly when grinding Trying to dress them back smooth is (as mentioned) difficult.
But I think I know what the problem is. It’s the speed that we lapidary grind at. 1750 rpm I believe that to be to slow to efficiently dress this type of wheel.
I’ve increased the speed and found the wheel dressed smoother, easier & quicker.
Anyway you’ll know what I’m referring to once you start experimenting.
You’ll want to purchase a dressing brick (fairly inexpensive) and a T-Handle diamond bar. Those tend to be pricey. Twenty bucks. But very useful.
The Fran tom will be an excellent machine for this…
Ed
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,155
|
Post by jamesp on Jun 5, 2015 5:47:54 GMT -5
I bought a hundred pounds of 6" X 1" SiC 60 grit grinding wheels at a junkyard. I crack them up for tumbling. I have mounted them on my 3600 RPM grinder for metal work. They are aggressive. And yes, I have successfully dressed them(at 3600 RPM). Poured lead holes, old school stuff : www.flickr.com/photos/67205364@N06/sets/72157649671884531
|
|
|
Post by mohs on Jun 5, 2015 8:16:06 GMT -5
That's a funny picture jamesp ! I never seen such an effective ring test really cracks me uP !
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,155
|
Post by jamesp on Jun 5, 2015 8:25:29 GMT -5
That's a funny picture jamesp ! I never seen such an effective ring test really cracks me uP ! That first photo, a close up of the particles, shows red and blue particles. Guessing colored corundum. Maybe mined natural material thrown in the mix. Those wheels may be 30 years old back when they mined the natural stuff. Glad to crack you up Ed.
|
|
|
Post by mohs on Jun 5, 2015 9:04:29 GMT -5
hey james I saw that you mentioned truing the wheels at higher rpm without much problems
I’m pretty proficient with truing wheels from my sharpening days & never recalled a problem
But on my cabber-- keeping that wheel running true-- is a task so I could only assume it’s the rpm speed
these are 1” wide wheels I also have ½” wide and those are not quite as difficult
|
|
minerken
Cave Dweller
Member since August 2013
Posts: 466
|
Post by minerken on Jun 5, 2015 10:26:51 GMT -5
I used SIC for years then switched to diamond I recomend that you use it for preforming but the SIC is a good way to start out. Like others have said they take a lot of dressing to keep the stone true, you need to learn how to use the edges and work your stone across the face so as to keep it even, not an easy thing to do as it will tend to get concave in the center this is also a good practice with diamond too as it will also tend to wear more in the middle if you don't it results in wearing it outfaster. I suggest an 80 grit diamond to start with then 220 diamond or Sic then 325-400 SIC or diamond then 600 and finally for prepolish worn out 600. Of course if you have more than 4 slots for the wheels you can go in steps up to 100,000 with diamond.
|
|
djaxon
starting to spend too much on rocks
Member since February 2015
Posts: 159
|
Post by djaxon on Jun 5, 2015 10:34:33 GMT -5
Thanks to you two for the input and advice. I'll be studying dressing brick and T-handle diamond bar. I also will calculate the speed for this machine. It has 3 options and I am currently using the center pulley. Thanks again.
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,155
|
Post by jamesp on Jun 5, 2015 12:56:09 GMT -5
hey james I saw that you mentioned truing the wheels at higher rpm without much problems I’m pretty proficient with truing wheels from my sharpening days & never recalled a problem But on my cabber-- keeping that wheel running true-- is a task so I could only assume it’s the rpm speed these are 1” wide wheels I also have ½” wide and those are not quite as difficult Betcha it is the speed of rotation Ed.
|
|
|
Post by mohs on Jun 5, 2015 13:47:11 GMT -5
|
|
|
Post by Peruano on Jun 7, 2015 8:07:47 GMT -5
No one has mentioned safety of these wheels so it seems desirable. Always spin them after turning off the water so that the water does not accumulate in the bottom and throw off the balance. Never stand in front of one when first turned on. When the explode or throw off a piece they can be lethal. Particularly watch when working on the edges (its easier to throw off small pieces if you grind improperly (or dress) to agrressively. There are actually several tools for truing or dressing these wheels. One looks like a steel rod with one or two diamonds on it. The other has a series of 4 or so wheels with diamonds and is wider. The key is to move it lightly and quickly across the face of the wheel wearing the ridges and working until all the surface is approaching the height of the grooves. You should use a 2x4 rest for the tool for security (so the tool does not go flying if it grabs the stone). These wheels work well if treated carefull - read a bunch of oldtime lapidary books, but you will probably want to switch to modern diamond wheels if budget and commitment permit. Enjoy the new machine and work safely. Ask lots of questions when appropriate. Tom
|
|
djaxon
starting to spend too much on rocks
Member since February 2015
Posts: 159
|
Post by djaxon on Jun 7, 2015 13:28:50 GMT -5
Thank you Tom. I really appreciate the advice and will continue to read up on "wheels" - Don
|
|
|
Post by johnjsgems on Jun 10, 2015 20:17:12 GMT -5
I had the same Frantom back in the day. I used the wheel type dresser by propping it against the front pan lip with both hands. It takes a really firm grip. I had neighbors at other end of street running outside to see what the racket was. I think the T-Bar diamond dressers are much easier to use. I would not go back to SC from diamonds. All that wheel material filling the sump (you don't get that with diamond wheels), the safety issues, and the ease of getting wheels out of shape. I lost a good 1/2" to 3/4" of wheel every time my son was there for the weekend using my machine.
|
|