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Group Project: Dividing Head - The Build
- Thread starter Flyinfool
- Start date
- Joined
- Mar 25, 2013
- Messages
- 5,220
Clever idea. I personally doubt I would use that. Any critical weird angle I would set with angle blocks for accuracy. I just don't want to screw up and be in the 30 deg slot when I need 45!
I'm glad you like it. It does look complex! Seems like it will be great for direct indexing.
- Joined
- Mar 25, 2013
- Messages
- 5,220
@Flyinfool - I am about to embark on the index plunger assembly and I need some guidance. In the drawings, the index body seems to be attached to the crank by a special nut. However, no nut is included in the plans?
The drawings have the index plunger assembly moving in the slot on the crank. This is fine but another alternative would be to have the plunger mounted in the end hole and have the slot ride on the worm shaft? That is how some other heads are made. Is there a disadvantage to that route? I also note that the index plunger must have enough travel to pull the pin out of the holes AND to clear the sector arms. I am thinking .500 minimum. I still like the idea of using a dowel pin to lock the plunger out like the other spring loaded plungers in the plans.
Anyway, a lot to process before I start! I may go off script again! Please chime in.
The drawings have the index plunger assembly moving in the slot on the crank. This is fine but another alternative would be to have the plunger mounted in the end hole and have the slot ride on the worm shaft? That is how some other heads are made. Is there a disadvantage to that route? I also note that the index plunger must have enough travel to pull the pin out of the holes AND to clear the sector arms. I am thinking .500 minimum. I still like the idea of using a dowel pin to lock the plunger out like the other spring loaded plungers in the plans.
Anyway, a lot to process before I start! I may go off script again! Please chime in.
- Joined
- Mar 25, 2013
- Messages
- 5,220
@Flyinfool -Thanks Jeff. That helps a lot. I see darn little material (.029") where the flats are? Should/could we make this larger somehow? What if we make the slot .600 and the nut accordingly larger? Unnecessary?
My crank arm is going to end up wider than .750 because of the eBay plates I bought. They have a .87 center hole so my spring needs to be larger diameter to accommodate. I will probably end up at a width of .875 or 1.000
My crank arm is going to end up wider than .750 because of the eBay plates I bought. They have a .87 center hole so my spring needs to be larger diameter to accommodate. I will probably end up at a width of .875 or 1.000
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- Apr 29, 2019
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That nut does not get much of any load on it . It is just hand tightened to hold the position in the slot. Of course you can make it bigger if you wish.
The odd dimension of the flats was so that the slot could be a standard size end mill.
The odd dimension of the flats was so that the slot could be a standard size end mill.
- Joined
- Mar 25, 2013
- Messages
- 5,220
Happy Sunday! I spent a little shop time making the crank.
I used a two flute end mill and got a nice straight slot.
I went reverse from the plans and threaded the hole for the pin assembly.
Sector arms are the ones that came with the plates. They are not gonna work. They are made for a 21mm shaft. That is fine (I made a spacer) except it necessitates a larger diameter spring. That, in turn, transmits more torque from the crank to the sector arms and causes them to rotate. That would be a disaster in flight. I think a smaller diameter spring will not have this issue.
One thing I have been seeing a lot with this project is how a small change causes a downstream problem that it hard to foresee.
I used a two flute end mill and got a nice straight slot.
I went reverse from the plans and threaded the hole for the pin assembly.
Sector arms are the ones that came with the plates. They are not gonna work. They are made for a 21mm shaft. That is fine (I made a spacer) except it necessitates a larger diameter spring. That, in turn, transmits more torque from the crank to the sector arms and causes them to rotate. That would be a disaster in flight. I think a smaller diameter spring will not have this issue.
One thing I have been seeing a lot with this project is how a small change causes a downstream problem that it hard to foresee.
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