There is no secrets here... Yes I used a C-Sink to produce the chamfer on the slots. I like the fact that I have one slot that goes straight through the center, I can use a long T-Nut and put a stud in the center for components that have a center hole.
Today I ground the top plate and then mounted the gear on the bottom. The plugged holes came out quite nice, you see they are there but not an eye sore.
Now I need to work on the base but tomorrow is beer day so machining might have to take the back burner.
Claude
claudef, proud to be a member of Metalworking Forum since Mar 2012.
(09-11-2012, 04:10 PM)claudef Wrote: There is no secrets here... Yes I used a C-Sink to produce the chamfer on the slots
Claude
OK, but how did you chamfer the rounded end of the T-slot so neatly?
Ed
The slot is 1/2 wide and the C-Sink is 3/4" dia. On the mill in the center of the slot you plunge the c_sink in till you get the required depth and feed it out of the slot, I did feed it back in towards the center to ensure better finish. This was a 6 lip c-sink and I think it was cutting on one lip only. Someday I should look at this and see if I can sharpen it. I can post a picture of the c-sink if required.
Claude
claudef, proud to be a member of Metalworking Forum since Mar 2012.
(09-11-2012, 04:10 PM)claudef Wrote: There is no secrets here... Yes I used a C-Sink to produce the chamfer on the slots
Claude
OK, but how did you chamfer the rounded end of the T-slot so neatly?
Ed
The slot is 1/2 wide and the C-Sink is 3/4" dia. On the mill in the center of the slot you plunge the c_sink in till you get the required depth and feed it out of the slot, I did feed it back in towards the center to ensure better finish. This was a 6 lip c-sink and I think it was cutting on one lip only. Someday I should look at this and see if I can sharpen it. I can post a picture of the c-sink if required.
Claude
OK, I understand how you did it now. Thanks for the explanation.
09-13-2012, 11:48 AM (This post was last modified: 09-13-2012, 12:12 PM by Rickabilly.)
(09-11-2012, 07:39 AM)stevec Wrote: I love the "chamfer" on the upper edge of the slots Claude, did you use a countersink for them?
I always (almost) give a touch of the countersink to holes I drill, especially if they are going to be tapped.
One little tip I was taught in Basic fitting trade course many years ago was to always counter bore the top of any tapped hole, drill it with a standard twist drill, of the nominal thread OD and to the depth of one "pitch".
This is done almost universally on production made tooling and gives that professional touch for nearly no cost, it also protects the top thread from dings, burrs and crushing and helps to start the tap square.
Just a tip,
Really lovely job on this little table Claude,
If I were you, and seeing how well you are able to graduate dials, I would think seriously about a vernier scale to go along with your very pretty degree markings, If you're not familiar with the method of plotting the correct spacings for the vernier scale I would be glad to run you through the process, just say the word. Just using the Vernier scale should let you measure directly to ).1 or 0.05 of a degree ,or if you are so inclined 3 or 6 minutes which would remove the need to graduate the hand dial, in fact you could even cut in both a decimal vernier and a minutes vernier at different points on the sub base ring.
Measuring directly off of the degree graduations is often a good way of reducing the confusion arising from back lash which can be difficult with worm wheels as the clearance can often vary at different points on the wheel or as a result of a slight eccentricity of the worm.
Are you going to use a disengage mechanism on your worm? you don't often see these on the baby rotary tables but with all the work you are putting in it seems like it'd be a waste not to.
I am about to go to your PDF now and check the calcs for the handwheel graduations.
Best regards
Rick
Whatever it is, do it today, Tomorrow may not be an option and regret outlasts fatigue.
Hello Again, I should have looked at the PDF before rattling on about the virtues of vernier scales, From what I make of the PDF it's not quite right, it seems that you may have confused decimals and minutes, with 10 vernier graduations over 7 degree graduations, rather than 11 degree graduations for decimal or 6 vernier graduations over 7 degree graduations for 10 minute increments.
The trick with vernier scales is to have ten graduations so 0 thru 9 just as you have, but the total length of these should be the same as eleven of the degree wheel graduations, I think you can also use nine but eleven is bigger so more accurate and easier to read, This will give you your 0.1 degree measure.
For minutes use 60 graduations over 61 on the degree wheel for minutes, or 30:31 for 2 minute increments, 20:21 for 3 minute increments, 12:13 for five minute increments or back to 10:11 for 6 minute increments(the same as decimal) and finally 6:7 for ten minute increments.
The beauty of vernier scales is that you can achieve really good accuracy without terribly expensive machinery.
On rotating vernier scales it is customary to use two scales one to the left and one to the right of the origin mark (the zero) so for decimal 0.1 degrees, that is a total of 19 graduations instead of ten, Zero as the centre mark with a 9 at each end of the scale, in truth 9 of these marks are duplicates and not really required but it looks nice and is easier to use.
Oh and one last thing, If you feel that it's all getting too tight to read which is common when you want to read minutes directly you can "Double size" the scale which does make it far easier to read, If you want to know how just ask, I've already taken up half the page and it is a bit of off topic.
Best regards
Rick
I can feel another how to thread coming on
Whatever it is, do it today, Tomorrow may not be an option and regret outlasts fatigue.
09-13-2012, 05:17 PM (This post was last modified: 09-13-2012, 05:18 PM by stevec.)
Rick I guess I forgot to mention that a good 90% of the holes I drill get a touch of the countersink on each side, if not for the reasons you do with the drill, then just for the esthetics. It just makes the hole look and work right!
Rick... Thanks for all the feedback.
c-bore on threaded holes, I have seen this many years ago, mainly on machine tooling, MOORE Jig Grinders if I remember correctly. I have never seen this on American tooling. I prefer the chamfer, one shot deal, 6 lip cutter does not chatter and gives a beautiful finished look. (beauty is in the eye of the beholder)
Disengaging the dial weighs heavily on my mind, it's not difficult to do but it does involve a dial cartridge (module containing the bearings, shaft and dials) with an eccentric. I have been sketching options for the worm gear shaft with an adjustable dial and the more i look at it the better the cartridge sounds. In this case I may put the eccentric on and have the worm disengage.
I dont want a vernier on my main RT (rotary table) I want an adjustable pointer for the degrees.
Now for the dial (you have to visualize the picture as a round dial), 9 degrees per turn (40-1 ratio) The bottom dial is graduated in degrees and 10 minute increments. The vernier breaks down the 10 minute graduations in 1 minute increments.
Now you have given me many Iterations of how I should graduate my dial and vernier and would like to consider these before I get to scribing but for the life of me I cant follow what you are saying in words.. could you possibly sketch out something and post it.
By the way, the plan was to scribe the vernier line 0 to 9 in the following positions:
Line 0=0
Line 1= 59 minutes
Line 2=1 deg, 58 m
Line 3= 2 deg, 57
Line 4= 3 deg, 56
Line 5= 4 deg, 55
Line 6= 5 deg, 54
Line 7= 6 deg, 53
Line 8= 7 deg, 52
Line 9= 8 deg, 51
claudef, proud to be a member of Metalworking Forum since Mar 2012.
machining might have to take the back burner.
