HOGLET Lifter Block

[richie garland]

I have milled the lifter block & preparing to drill the lifter holes. The plans give the location from the rear to the front for the holes but not from the side to the center. I know that it has to be at 23 & 29 degrees, but I am uncertain exactly where from side to center to drill. If anybody else has built the Hoglet Twin V please respond in as simple English as possible. I would really appreciate any info out there.

 

[Jasonb]

If you do it in a rotary table using the holding jig you just centre the work and rotate to the angle required and then drill, no need for a measurement.

If you are trying to do it by holding the block at the required angle in the vice then you will need to use trigonometry to work out the distance - over to Marv

Jason

 

[T70MkIII]

If the information isn't already here, drop Kevin a line:

http://www.homemodelenginemachinist.com/index.php?topic=1831.0

 

[richie garland]

Can you give me the correct trig formula? I do not have a rotary table.

 

[Jasonb]

Have you machined the two top faces back to 25deg yet? as it makes the maths a lot easier if the top is still flat therefore giving a right angled triangle with both length of one side and angle known. If its already cut then we only know the angle which makes it a whole lot harder.

I have PM'd Marv who is the maths guru and sent him a copy of the drawing

J

 

[Jasonb]

There is actually another way to do it

Make the holding jig like it shows

Hold the jig in your mill vice and set it central to the axis, don't move the Y axis again.

Now loosen the jig in the vice and rotate until the work is at the correct angle, tighten vice and drill

Repeat for the other holes.

Doing it this way keeps all the holes aimed at the centre line and there is no need to calculate their sideways position, its just a bit easier with a RT

 

[mklotz]

I looked at the drawings Jason supplied and I don't see any convenient way to determine the offset accurately with trig. If one started with a cylindrical piece of known diameter and drilled the holes first, then the calculation would be straight forward but with that roof-shaped profile and the print dimensions, it's not simple.

The part was obviously designed from the get go to be made on a rotary table. Lacking said table, I think Jason's reply #5 technique, or some variant thereof, is your best choice.

 

[Jasonb]

Thanks Marv

J

 

[richie garland]

Thanks for all the advice...I managed to acquire a rotary table, made the cam housing fixture, and I remade the lifter block with a flat top....here is where I am a bit confused...should I center the rotary table, then center the jig on the RT, then center the lifter block on the jig; detach the rotary table and reattach at 90 degrees, and square it up, turn the rotary table to 29 degrees and drill?

 

[Jasonb]

Set the RT up vertically and make sure it is square across the mill table front to back and teh RT axis is centred on teh mill spindle. Lock the Y axis

Mount the block onto the jig it should be self centering if the underside has been machined first

Mount the jig centrally onto the RT, if it has a chuck this will be easy. Also ensure the RT is set at zero deg and the top of the block is horizontal.

I then rotated mine to 25deg each way and machined the sloping faces followed by doing the holes as it saves having to start the hole at such a steep angle.

Jason