Member postings for Huub

Jouke,

Gentlemen,
May women not reply

The blank was quickly pressed against the chuck by means of a mandrel in the tail stock.
If you do this, you have to use very little pressure because the raw blank it self is not flat. Have you removed the burs from making the mounting hole? Have you removed the burs from making the chamfer?

It decreased to 0.03mm, so not so much improvement.
From 5 to 3 is 40% better, you are on the right way

My procudure for this would be:

• Face the blank, drill the hole (- 0.1 mm), chamfer the blank, chamfer the hole, do a last facing pass.
• Turn the blank to do the other side
• Face the blank, chamfer the blank, chamfer the hole, do a last facing pass.
• Ream or drill the hole to remove the burs from chamfering and get right the diameter
• Give the blank on both sides a few manual grinding passes using an old worn 400 grid diamond grinding plate (1 mm thick)

I have checked a M20 washer 40 mm diameter, 4.83 mm thick, that I faced using the above procedure a few months ago. Thickness spread 4.82..4.83 mm. This was done using a taper in the spindle bore as I explained before.

• Have you faced both sides of the blank using the super glue method
• Did you use a HSS tool or Insert (Carbide)
• RPM
• Cutting depth
• Thickness of the blank
• Has the blank a really smooth finish
• Have you checked the cross slide play. Any play will lead to thickness variations.

Regards, Huub

Edited By Huub on 14/02/2022 22:26:50

Ok, Now I get it.

Strange but if its working...

Just search on "magnifier scale led" at google, amazon, aliexpress, etc and you will find some examples

I use this 10X magnifier that has a scale to inspect tool tips and other small stuff.

Magnifier

Youke,

I have found your calculations and this is an interesting approach.

My first thoughts are that you want to mill an ellipse by placing the mill (button) at an angle. This way you can approach the desired tooth form more accurate than by using a mill or button the common way.

Question:

How do you know the dimensions of the ellipse that best fits the required shape.

Making such a cutter is not so simple but doable:

If you rotate the head of the mill, you will lose your position and setting the right position is very difficult as I experienced some time ago.

Placing one button at the right angle is doable. Placing the other button at the same angle is also not a problem, just reverse the tool 180°. Getting the right distance between the two buttons is very difficult, but using 2 separate tools is not a problem. So I think it is doable.
You could also mill one side of the two seperate tools until the distance between the buttons is OK and than bolt them together.

The benefit:

I expect that the extra accuracy you gain by making an ellipse will be lost once you cut different tooth sizes (12,13) using the same gear cutter. So the real gain will be only for the first gear in the range. Because making a cutter on the CNC lathe is so easy, I make a cutter specific for each tooth count.

If I look at the tolerances the cutters a made (D+f = 2.16) I expect that in the end the gain is little. The tolerances on clock gears are even greater.

How to check the result:

A way to check the real benefit is to design the gears in CAD made in different ways and check the differences.

Regards, Huub

Youke,

what do you think of my elliptical calculations?
I haven't seen your calculations. Mine (involute gears) are based on the Ivan Law gear cutting book, Mikes work shop and probably some more information I have gathered from the Internet.
I will send you my spreadsheet by PM. The documentation is in Dutch but that won't be a problem for you. Once I have translated it to English, I will place it on Git so that all can benefit.

I check my calculation by drawing the involute gear in cad and then add my own tooth profile. That makes it easy to see the differences.

hessmer spurgear builder

Mikes workshop

Ivan law gears and gear cutting

If the form tool is given a very small non-zero curvature behind the “frontradius” then you will already introduce a clearance for the “flanks” of the gear cutter.
Only if this flank is wider than the tip, otherwise the tip will remove the material.

Perhaps with some kind of tangential cutter with a round toolbit.

However, as soon as the tangential tool cuts further than half its long elliptical axis then you get parallel flanks again.
I aggree

Meaning that you can not cut high enough teeth?
The Clock tooth has a pretty long parallel part. Basically, this part will be cut by the tip of the cutter. The tip has clearance so that is not really a problem. As long as the tip is sharp, cutting wil not be a problem.

I think even without clearance these cutters will do the job because all cutters made using an eccentric mount have the same problem and are still used with good results by a lot of clock makers.

The cutters I make for broaching a keyhole on the lathe, by design, have only clearance at the tip, not at the parallel sides and therefore they work pretty good for this task.

In the video I am making, I will show an easy way to make these clock gear cutters, having clearance on all cutting edges, simply by manual milling. I am very anxious to see the difference between this type of cutter and the once made the old way.

Edited By Huub on 11/02/2022 22:24:07

Edited By Huub Buis on 11/02/2022 13:45:47

Jamie,

I think is is a good idea to start using HSS tools. You have to learn how to regrind and shape them. This is something that will be needed some time. HSS tools are also cost effective (if you don't calculate time). I spend yearly more on inserts than i totally spend on HSS tools.

Youke,

I measure thickness differences up to 0.05mm
I expected the difference a lot smaller because the backface of the chuck normally is quit good/flat.
If you clamp something against a surface, then after tightening, you should tap it lightly with a hammer (wood/plastic) to get rid of all play.

Is it an idea to use a “super glue” chuck for facing
If you face the alu this should give a result better than 0.02 mm. Beware that when the glue gets hot/warm the part gets off. You also have to remove all the glue (acetone or nail polish remover)
I normally use glue only for small parts that can't held by a chuck or collet.

You can measure the flatness of the chuck (after removing the claws) to see if this chuck really can be the cause of the problems.
If the chuck isn't flat you have to check the back of the chuck and the mounting plate for chips, burrs and other damage.

If I want thin parts turned really flat, I place a taper (having a long bar at the end) in the lathe and face it. Then I press the part against this this face when I clamp it in the 3 or 4 claw chuck. Normally, the flatness than is better than 0.01 mm.
I make the size of the bar just a bit smaller then the part to clamp. In the bigger lathe, I can place the taper without removing the chuck, in the small lathe, I have to remove the chuck first.

Jouke,

As you understand my cutters do not have a clearance for the parallel parts of the teeth.
To me, it seems you also turn the cutter eccentric. If the front of the cutter tip is tapered, you have clearance on all cutting edges.

It would be nice to see some pictures showing your two ways of making gear cutters
I will make some pictures of my setup on the lathe, the mil and a turned gear cutter at the end of this week.

Where do you live about in The Netherlands
I live in Hoensbroek, in the south of the Netherlands.

If you can turn a radius on the lathe, you can turn these gear cutters without CNC. Compensating for the nose radius of the tool is not that complicated but you can avoid this by using a sharp HSS (parting) tool.

Keep your tool as close to the tool post (less stickout) as possible. Turn the topslide as far backwards as possible. This gives a more rigid setup.

I like your setup using a bearing in the steady rest, haven't seen this before!

Regards, Huub

Your cutting depth = D+f = 2.16 for a Modul 1 gear. The 0.16 (extra cutting depth) creates play between the gears. If you have a 20° pressure angle, this results in a clearance at 1 flank of (tan 20 x 0.16) 0.06 mm. At the 4 flanks there is 0.23 mm clearance total.

A 12 teeth Module 1 gear has a tip of 1.10 mm.

A 60 teeth Module 1 gear has a tip of 0.82 mm.

You could place the tool upside down at the backside of the lathe. Then you don't need to change the rotation of the spindle.

I assume you are making involute gear cutters using the "button method".

I make single tooth versions on my CNC lathe. I measure the tooth thickness using a caliper. I set the caliper to the requested diameter + 0.1 mm. The cutter tip should "lock" between the "legs" (don't know the English word) of the caliper. Then I set the gap 0.1 mm smaller than the requested size. Now it should not be possible to "lock" the tip of the gear between the "legs" of the caliper. By changing the gap between the "legs", I can "measure" very repeatable the tip of the gear.

I also made these cutters on the milling machine. An end mill is used as "Button". Instead of calculating the button diameter for the gear cutter to make, I calculate the the number teeth, based on the end mill diameter.

A 4 mm end mill can make a Modul 1 cutter for 12 (11.7) teeth and more.

A 5 mm end mill can make a Modul 1 cutter for 15 (14.6) teeth and more.

A 20 mm end mill can make a Modul 1 cutter for 59 (58,5) teeth and more.

Edited By Huub Buis on 07/02/2022 22:48:35

Steve,

Beware that the 0.15 mm error also includes the bending during turning. That can be significant when turning such a long bar.

I prefer using an aluminium tube (thick wall), an insert for aluminium (sharp) and a shallow cut of 0.02 mm.

I have made a few videos on measuring the alignment of a lathe. I hope it is of any help.

Measuring lathe alignment

Huub

Edit,

I have a similar lathe (290 kg) that rests on 2 stands (Left & Right). Assuming the bed was grinded on these stands, placing them on a flat surface without bolts the bed should be straight. So my lathe is not bolted to the table (just secured loosely) and the misalignment is about 0.016 mm/ 100 mm.

Edited By Huub Buis on 06/02/2022 22:02:54

I use modified versions of grbl for some years now for both my lathes and rotary table.

grbl-L for the small lathe: **LINK**

grbl-l-mega for the larger lathe: **LINK**

Grbl_ESP32_R for my rotary table: **LINK**

I have documented the CNC mods of the small lathe. The CNC build was done for about 100$ (today probably for 150$) **LINK**

Any questions please ask