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Member postings for Gustav Thiesen

Here is a list of all the postings Gustav Thiesen has made in our forums. Click on a thread name to jump to the thread.

Thread: Modified jacobs gear cutter upgraded
03/08/2018 17:04:44

Here i have a better looking Video:

Edited By Neil Wyatt on 03/08/2018 17:49:55

02/08/2018 21:41:49

For my example of the Jacobs Machine I have used waste pieces of mild steel which i got from a metalworking company.
So i didn't follow the construction plan and choosed greater dimensions for the three components of the machine.
After reading the articles of Chris Robinson i upgraded the normal gear train by the differential gear train.
This version was able to cut gears in good quality until a diameter of 8 cm. Beyond this the cutting was running mechanical unstable and the cutting process was often interrupted.
The cutting of a 127 teeth gear in modul 1 was a difficult affair. I contacted Chris Robinson. He confirmed that this little machine could deliver good results up to modul 1,25.
After a further check of my machine i decided to introduce four impovements for better results with big gears:

1. A counter-Bearing for the gear-cutter
2. A counter-Bearing for workpiece-axis
3. Different heavy flanges 8cm / 6cm / 4,5cm / 3cm / 2cm in diameter for a better fixing of the gear blancs.
Some quick-release axles and many adapters for different bore diameters.
4. Correction of to much play of the worm screw

The aim was to correct the mechanical instabilities when cutting big gears. The attached pictures will show you the four places for my uprade. The simplest and most effectiv step was the correction of the play of the worm
by using some adjusting washers.
The link of the video will show the cutting of a big gear modul 1,25, outer diameter 140 mm with 110 teeth.
The video is showing the cutting process at a depth of 0,9 mm, later you can see the last cut, depth 2,7 mm.
After the upgrade improvments the cutting could be finished with a great reduction of mechanical instability and without any interruption.ganzseitiges foto2_seite_2.jpgganzseitiges foto2_seite_3.jpgganzseitiges foto2_seite_4.jpgganzseitiges foto2_seite_1.jpgganzseitiges foto5.jpg**LINK**

Thread: A differential gearbox for my hobbing machine
17/02/2017 15:07:09

Excuse me, I'm not used to the conditions of the forum. Some text has disappered.

I must say that the first version of the machine with two shears was instable, because the work was done only with the help of my hands to keep the shears calm.

17/02/2017 14:58:53

Many thanks to Chris Robinson!

In February 2016 i asked in this place for background informations about a gear train capable to produce prime number gears.

At i found a version, which was equipped with a differential gearbox helping to produce prime number gears. The first answers didn't help. So i decided to make a copy of the jacobs
hobbing machine with o normal gearbox.

But in my mind a wish list with two features was still opened:

1. Creation of a planetary gear in the form of a bevel gear differential.
2. Additional supplements to enable helical gear manufacturing.

As far as part 2 is concerned, I am not yet surely determined, since another way by making a connection with one of my dividing attachments with my Milling machine in the sense of a spiral milling device would also be an acceptable way.

The implementation of Part 1, however was difficult to understand, in particular the mathematical
Conditions. After several months' waiting time the author of the article in,
who is the only one having created a differential gear for the Jacobs machine found my questions and agreed
to help me, especially giving informations about the mathematical foundations.
Thus there was no longer any obstacle to dare to build.

For the bevel gear differential, 4 identical bevel gears were used according to the method of Ivan Law
(20 teeth, module 1), the corresponding spur gear with 40 teeth, module
A second shear was quickly created. The first disappointment followed at the same time, as the two
shears proved to be very unstable. A somewhat bumpy run was only possible with hand- and power-
Support. After all, the fundamental running was given.




dscf3471.jpgdscf3472.jpgThus a more stable gear set-up had to be achieved.
Compared with the examples on MEW, an additional idler gear on each side was required, because I had right turning hobs and I wanted that the hob was turning towards the gear blank.
Due to the fact that a fixed size was assigned to each intermediate wheel on each side, a relatively short and stable shear was provided for the second variable idler.


On youtube you can see the machine hobbing a 127 teeth gear.


Edited By JasonB on 17/02/2017 15:03:14

Thread: Gear hobber (mechanical)
25/10/2016 13:21:23

To Chris Robinson:

Thank you very much für your post. I'm very interested in the basics of your differential add-on. So I would be pleased to receive your informations. Perhaps you can give me some tips of the design of the add-on too.

11/08/2016 13:08:13

I bought the CES Plans a couple of months ago and now I try to manufacture the different components of the machine. There is one problem with the feeding of the working head carrying the gear blank which I don't under-stand. The video "little hobbing machine" doesn't show this action.

My question is: How can I bring back the working head to the start position after the first feeding of the gear blank, to begin the next feeding with the condition to find the same cutting groove.

29/02/2016 16:34:14

Hello, Duncan, Your spreedsheet seems to give a very good explanation. I will study it this evening. Another source with basic knowledge is this:



Many thanks!

29/02/2016 12:11:49

to Duncan Munro:

Many thanks for this long explanation. I must confess that my competence in English language sometimes comes to a border because I learned it fifty to sixty years ago. So I must have more time to understand what's about your chaps explanation. I will repeat reading what you have posted for some times until I will be back.

28/02/2016 12:27:46

To John Stevenson: I'm looking for this differential addon of the CES hobber. Can you give more information about the construction and the use of this addon or otherwise do you know whether the plans of collegeengineering will give this information?

26/02/2016 17:02:05

Many thanks Duncan!

My special aim is not to make a 127 teeth gear. This is only one of the possibilities. My main target is to build up a hobbing machine, which should be able to cut prime number gears to. One reason for this is, that I have made a dividing head last year. Because it should also manage prime numbers, i made a compound dividing head. But when it was finished i saw that the handling was prone to errors. So I have transformed the construction to a differential dividing head. I had to cut 12 gears for this. I made them by poor mans hobbing method. To facilitate and to get better results I want to make this machine.

25/02/2016 07:09:07

To Engine Builder:

If use a 40 teeth gear as index gear the hob will cut 40 teeth in the blank with one revolution. This is because of the coupling by the idler gear. If I change the idler gear by two gears on the same stud, which will deliver a translation of 1,5 you will get 60 teeth by one revolution. But these teeth are not complete, it will start with little notches which will be greater by feeding and get deeper by repeating passes.

24/02/2016 17:15:11

To Engine Builder:

I'm not able to give you a formula. The mechanical way to do this is based on two arms:

1. you have a gear blank and the cutting hob

2. you have a dividing gear connected with a worm

The two are connected by an idler gear. If the dividing gear has 40 teeth, the cutting hob will also cut 40 teeth. If you want to have a 60 teeth gear, you must replace the simple idler gear by compound approach with two gears which gives a translation of 1,5. I hope you can understand what I mean, I have learned English more than fifty years ago.

23/02/2016 12:55:56

Many thanks for this information, but I'm visiting for a couple of years. This is a very good side and i know the side concerning the Jacobs machine. There is only a picture of the "differential addon", but no further information.

Some members of the forum have answered to my first question misunderstanding the term "differential addon".They thought that it was pointing to a special form of dividing or dividing head. In this case the term is better compared with the differential bearing of a car equipped with some bevel gears in order to transmit different speeds. All I want to know is, wether the kit or the plans of college engineering will give sufficient information to built and to use this differential addon in order to hob prime number gears. This differential addon is a later invention, the first plans from 1976 didn't deal with the production of prime number gears.

21/02/2016 21:21:52

Many thanks for the posts. I hope that Mike Haughton will help with information. I'm more interested in the old- fashioned way with a gear train, i think that I'm to old for the electronical way of construction.

21/02/2016 14:28:45

I'm looking for information about the gear hobber of college engineering.My special interest is pointed to the production of prime number gears, for example the 127 teeth gear. Now i want to know, whether the kit or the plans form college engineering will give enough information about the construction of the differential gear addition to the jacobs gear hobber.

My email request to college engineering to answer this question was not responded until know.

Is there any member of the forum to give me more information?

Thread: Dividing Head
16/08/2014 18:54:06

I'm looking for plans of Ivan Laws differential dividing head (MEW 57). Is it possible to buy the instructions for

building this project.?

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