What size of forearm do you start with when cutting point grooves?diameter of both ends and length

How long of a groove do you cut?

How long is the point wood you start out with?

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- Thread starter HDR10
- Start date

What size of forearm do you start with when cutting point grooves?diameter of both ends and length

How long of a groove do you cut?

How long is the point wood you start out with?

Hi,

Here is what I use for sizing dimensions.

Tapered Forearm joint end @ .925

Forearm Length @ 15" to 15.5" depending if how you hold the piece in the indexer. The forearm wood can actually be as small as 12 1/8" if you consider tenons or core dowels extending. These factors you need to work out for your set up.

Groove Length @ 10.5"

Point stocK @ 10 3/4"

When you set up your mill the length of your groove will be determined by your angle of the table. You have to play with that and make some samples until you get what you want.

I have predetermined holes drilled in my table for dowels so that I can index 4 or 5 points geometry set ups for repeatability for my cues.

When setting up you grooves, don't forget to figure the joint collar and ringwork into the equation. I leave a little extra stock on each end of the forearm for this reason. When you turn the piece down the point will retract also.

Here is a tip for veneers. If you like the look of very high point stock ends under the veneers, don't exceed .120 on the combined thickness of your glued veneers. The point stock hight deferential is about 1.250 if you use 4 X .040 compared to 4 x .030 veneers.

Good Luck,

Rick G

Here is what I use for sizing dimensions.

Tapered Forearm joint end @ .925

Forearm Length @ 15" to 15.5" depending if how you hold the piece in the indexer. The forearm wood can actually be as small as 12 1/8" if you consider tenons or core dowels extending. These factors you need to work out for your set up.

Groove Length @ 10.5"

Point stocK @ 10 3/4"

When you set up your mill the length of your groove will be determined by your angle of the table. You have to play with that and make some samples until you get what you want.

I have predetermined holes drilled in my table for dowels so that I can index 4 or 5 points geometry set ups for repeatability for my cues.

When setting up you grooves, don't forget to figure the joint collar and ringwork into the equation. I leave a little extra stock on each end of the forearm for this reason. When you turn the piece down the point will retract also.

Here is a tip for veneers. If you like the look of very high point stock ends under the veneers, don't exceed .120 on the combined thickness of your glued veneers. The point stock hight deferential is about 1.250 if you use 4 X .040 compared to 4 x .030 veneers.

Good Luck,

Rick G

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Good post Rick. What about depth of the cut?

Sent from my iPhone using Tapatalk

Sent from my iPhone using Tapatalk

Good post Rick. What about depth of the cut?

Sent from my iPhone using Tapatalk

Hi,

Depth of cut is a function of the table angle. If you go too deep the point end will run off the front or you can cut through the centerline.

I used the A-Joint gap as my guide when I set up my table geometry. On my 4 point cues I have about a .040 gap between points/veneers at the A-Joint. On my 5 point cue it is .025.

Rick G

Good post Rick. What about depth of the cut?

The depth of the cut is determined by the angle of the table.

The formula is: A sq plus B sq equals c Sq (Pathagoriams theroem),

where side B is the depth, side A is the length of the point grove (centerline) and side C is the length of the side of the groove which is determined by the angle of cut to the centerline (side A). So, the longer side C is the deeper the cut (side B) will be.

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Good post Rick. What about depth of the cut?

The depth of the cut is determined by the angle of the table.

The formula is: A sq plus B sq equals c Sq (Pathagoriams theroem),

where side C is the depth, side A is the length of the point grove (centerline) and side C is the length of the side of the groove which is determined by the angle of cut to the centerline (side A). So, the longer side B is the deeper the cut (side C) will be.

That is a great theorem, another one is Trialbyerrorium theorem. Start around 1 degree angle and work up from there until you reach desired look. When you have a few test pieces under your belt it will all make sense.

That is a great theorem, another one is Trialbyerrorium theorem. Start around 1 degree angle and work up from there until you reach desired look. When you have a few test pieces under your belt it will all make sense.

Actually, I believe you have it just exactly backward. The way I determined the correct angle so as to have the points touch each other at the A-joint on a 4 point cue is to take a tapered dowel with the exact final measurements of one of my cues. Say it is 1 inch at the A and .850 at the joint. On my jig, that pivots exactly where the A-joint would be, I route a V-groove to the exact center of the prong at the A-joint and with the prong off-set at a oblique angle. This will make a short but deep V-groove. Now I just start moving the joint end of the prong more towards straight angle and make another cut which will make the point the same depth at the A-joint but now longer in length. I do this again and again until I finally have the length of point that I desire and I mark this angle down and every prong I make in the future, immaterial as to it's girth, will have the points come out exactly at this predetermined length. I marked down the exact distance from the end of my Table to a spot on the jig so that when I mount the jig onto the table I set it up at this exact distance. On my mill and jig this happens to be at .517 for points touching at the back and 9.500 in length. I've got other distances marked down so that I can make points 8.0, 8.5, 9.0, 9.5 and 10.0 inch. As has already been stated, to make the V-groove go to the exact center of the prong, only two grooves can be cut at a time and they must be opposing each other and then the point glued back in and the groove filled so that the prong will be stable enough so as to be able to cut the remaining two V's.

Dick

Sorry!!! Posted under wrong thread.

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