Making a duck call jig

[JScott]

A friend of mine at work makes duck and turkey calls in his spare time at home. One of the items that helps is a metal jig that is used to shape the barrel of a duck call accurately and quickly. I offered to make a prototype for him to try since the commercial ones available for sale are pretty expensive.

This is what I am trying to create.

   

   

I have some small blocks of 4140 pre hard so I started with the smallest one.  This was a good chance to use my indexable end mill.  It has two TPG222 inserts.  I just wanted to get rid of the scale and rust on the outside of the block and get things squared up.

Here is a first pass using some dark cutting oil.

   

After I got the sides cleaned up I started on the ends.  The ends were rough saw cut and were not very square.  To get things aligned in the vise I gently clamped the 4140 block to a small angle block.  I rested the bottom of the work piece on a single steel ball so it could tilt and pivot while everything was tightened up.  As I gently tightened the vise I tapped the block with a nylon dead blow hammer.  Then I tightened the C-clamp again.  Then really snugged down the vise.

   

You can see the steel ball under the work piece.

   

And taking a pass on the end of the block.  The end mill was making nice 6 and 9 shaped chips.

   

The finished product from yesterday.  Not great but not bad.  Next up will be to drill and bore the hole.

   

   

[DaveH]

Looks good
 
DaveH

[JScott]

I made a little progress over the weekend.  This jig requires a 0.625" through hole.  I drilled a pilot hole 1/2" with a twist drill and then followed that with a 0.625" end mill.  It worked well but I had to peck "drill" the last portion of the hole because the end mill flutes filled with chips.

   

This is how it looks with the hole chamfered.

   

[TomG]

Looking good. Some progress is better than no progress.

Tom

[JScott]

I hit another lick yesterday.  I used my Horror Fright horizontal/vertical bandsaw to rough out the bulk of material for the step.  Then I started a new adventure with the "spindle hammer" to machine down the two surfaces on either side of the trough.  I upped the rpm's to 1500 and got a much nicer surface finish.

Next will be machining the rear step and then milling the 0.165" notch in the corner of the "L".  It's supposed to rain next weekend so maybe I will get more time in the shop and the turkeys will get a weekend reprieve.

Here is the jig with the rough, saw cut faces.

   

Here are the homemade spring clips made from steel strapping tape that I use to keep the parallels upright and tight against the vise jaws.

   

And a final picture of the finished lower step.

   

[JScott]

I hit a window of opportunity and made a little more progress on the jig last night.  I was able to finish the "upper" step with a regular end mill.  It doesn't have as nice a finish as the carbide indexable end mill.  Tried different rpm's and depth of cut and they were all about the same.  I was able to hit the size though.

This picture shows the surface finish.

   

Here is the jig in the normal orientation.  Still need to add the little slots in the corner.  Should be able to start this weekend.

   

[Highpower]

(03-17-2016, 12:34 PM)JScott Wrote: I hit a window of opportunity and made a little more progress on the jig last night.  I was able to finish the "upper" step with a regular end mill.  It doesn't have as nice a finish as the carbide indexable end mill.  Tried different rpm's and depth of cut and they were all about the same.

Try using the side of the end mill for your finish passes instead of the mill end. You might find the finish more visually appealing.

[JScott]

Thanks for the 1¢ tip Highpower.      I'll see if my end mill is long enough to try that on the next one.

My new goal is to get a 2¢ reply!  I do appreciate the help.

[TomG]

It looks like you may have hurt your HSS end mill. It should be producing a beautiful finish on that steel, but the cutting speed has to be kept around 60SFPM for a HSS end mill, or it will burn up. Coolant or oil are a good idea as well.

Sawing out the piece was good. It's temping to mill it out, but that's not very efficient. You need to be careful with cutting speed on the saw as well or that pre-hard will kill the blade. It should be 60SFPM there too (with coolant).

How are you planning to cut the slot?

Tom

[JScott]

TomG,

I saw cut the waste material at the lowest speed on the HF band saw and used a lot of WD-40 to keep it lubricated.  It cut easily and when I cut the last bit by hand using the saw vertically very little pressure was needed.

My end mill could be dull because the carbide insert end mill left a much better finish.  I always use some dark cutting oil with the end mills.  It smokes a little but I don't mind the smell and I have a small fan set up to blow it away.  I'll do some experiments with the scrap block I cut out with the saw.

My plan for the slot is to pre-drill holes with 1/8" drill bit and then use a long 5/32" end mill to remove the rest of the material.  I am also looking at making a 0.165" broach from a square 3/16" tool bit and using the mill to nibble out the remaining material in the corners at the back of the slot where the end mill will leave a radius.  I'll probably just file out the corners because there will be very little material and I've never made a broach before.  But, like all things there is always a first time.

JScott