Clever idea?

[Don Case]

I'm building some bitts and other parts that require some sheaves put into a timber. See picture. I've got no problem building the parts except for drilling the hole for the sheave axle/pin. Is there a really slick method of getting that thing right in the middle lengthwise so that the sheave doesn't bind up on one end or the other?

 

[DARIVS ARCHITECTVS]

Careful measuring is the only way I know of ensuring that the sheave shaft is centered where you want it. If the tolerance are really tight, start with a small pilot hole and see where that puts the sheave. Using a rotary Dremel tool, mill out the hole larger with pressure biased against the side where you want the hole to wander toward as you cut. Use the larger drill bit of a size equal to the sheave shaft for the final cut to round out the hole. By enlarging that pilot hole in the correcting direction, the final cut should be on target. It gets easier and faster with practice like most other things. (Ratlining still sucks though... no changing that. )
If you still can't get the sheave in the center of the slot and it still rubs when test fitting, you can always file a tiny bit off the end of the slot where it's making contact and free up the sheave.

 

[Don Case]

Thanks Kurt

 

[Uwek]

The most safe way is drilling in a mill where you can be sure, that your drill bitt is exactly vertical drilling.
If you do not have a mill I would drill like Kurt mentioned with a smaller drill first as driving hole and later with a bigger drill diameter.
What is also helping to reduce possible errors in the angle:
Drill the holes in two steps from both sides. So first the direction of the red arrow, than turn the part by 180° and drill the green arrow.......
Try it - it is helping a lot

 

[Don Case]

I do have a mill so I will do it there. In this case I can't drill from both sides as I've already assembled the bitts. (Yet another thing I have trouble with )
Now I just have to come up with a way of getting the sheaves a consistent thickness. Another measuring difficulty. Hmmm I thick I'm zeroing in on what my difficulty actually is----- measuring accurately and transferring those measurements.

 

[bill36]

I'm building some bitts and other parts that require some sheaves put into a timber. See picture. I've got no problem building the parts except for drilling the hole for the sheave axle/pin. Is there a really slick method of getting that thing right in the middle lengthwise so that the sheave doesn't bind up on one end or the other?

View attachment 326792

1. Yes! measure a real block (or a good picture of a real block) of the period. Lay the dimensions out on a full-size drawing (include the rope).
2. Calculate the scaled down dimensions (at 1/48, 1/96, etc) and use these new dimensions to make another 'scale' drawing (of some large size); you want to make sure the scaled dimensions produce the same picture as the measured dimensions.
I usually use 1/4inch ruled 8x11 inch sheets from a wire bound notebook for all this drawing.
3. Use a 0.001" dial caliper (available on Amazon.com for about $20 to $25 USD ) to transfer the scale dimensions to your wood.
4. Drill away.
5. Check the dimensions on your finished product with the caliper.