Crag Lapiana, of Chefwarekits.com, is now the U.S. distributor of the EZ "Pro" Threading Jig.  Craig recently contacted me, requested that I do a review of the jig, and offered to send me a prototype of the new model.

I have hand chased threads, but have yet to spend the time it takes to become proficient at the process.  The idea of gaining the consistency possible with a jig and the time saved in doing multiple pieces encouraged me to consider his offer and I agreed to do so long as we both understood that my review would be independent, without compensation, and without obligation to him or to the manufacturer.

There are other threading jigs on the market, including two often mentioned.  The Willard Baxter Thread Master, in the size appropriate for my Jet 1642 is $569.99.  Thread sizes available are 24, 20, 18, 16, 14, 12, 10, or 8 Pitch.  The Bonnie Klein appears to be available only in one thread size, and intended only for mini lathes.  The cost is $435.75 if payment is via PayPal or credit card.  Cost for the EZ Pro, as tested with only one size Spindle, is $259.

I do not intend this to be a comparison review, as I did not have access to the Baxter or Klein jigs.  However, all of these threading jigs operate under the same principle and the process of using them appears generally the same.  As opposed to hand chasing where the work is spinning in the lathe and the cutter advances into the work, using a jig, the work is advanced into a spinning cutter.

One substantial design difference among these jigs is that the EZ Pro mounts in the banjo of the lathe.  This permits one to cut threads in work the diameter of which is limited only by the movement of the banjo.  Both the Baxter and Klein jigs mount on the ways of the lathe and the maximum diameter of the threaded work is limited by the amount of possible adjustment/movement in the jig.  This may not be a serious consideration, as wood movement becomes a factor to consider on going much over 2" in diameter for a mating set of threads in face grain wood – or, for that matter, even in end grain orientation (not really suitable for wood threads.)

However, there is a trade off for this mounting method.  With any threading jig, one must align the jig to achieve the following:

  1. The center of the work must be the same height as the lathe spindle.
  2. The work must be the proper distance into the cutter to achieve the proper depth of cut for the thread size used.
  3. Moreover, the work must advance in to the cutter in a plane parallel with the ways of the lathe.

With the Baxter and Klein jigs, the jig mounts on the ways and presumably, the travel of the spindle, or the advancement of the work into the cutter, is controlled and always parallel to the ways.  There is no adjustment needed or available from what I can observe in the information available on those jigs.

With the EZ Pro, one must visually align the axis of the spindle with the ways each time the jig is used.  While not that difficult to do, one must achieve reasonable tolerances to assure a consistent diameter on the threaded stock.  Failure to do this will result in tapered threads.

 

It would be helpful at this point to refer to the Parts Diagram image found on the website - http://www.threadingjig.com, along with the parts listing.

  1. Spindle Hand Wheel
  2. Main Spindle
  3. Cross Slide Lock
  4. Main Jig Body
  5. Chuck Nose
  6. Cross Slide
  7. Cross Slide Feedscrew
  8. Jig Post                   
  9. Height Setting Ring

 

Craig included the Main Spindle in the three most popular sizes – shown in the photo below from left to right – 20 tpi, 16 tpi and 10 tpi.  The jig is available in 24, 20, 16, 12, 10, 8 tpi, and when purchased, you must specify the thread size, and will receive only one of the Main Spindles.

 

Also included were the collet, and a 60 deg Thread Cutter (HSS) with a 3/8” shaft.  The washer and wing nut for the draw bar were included, but not the all thread bar, which I obtained from the local hardware store.  It is standard 3/8" with 16 tpi thread.  Although the rod appears somewhat distorted by my poor photographic skills, it is actually straight!

Craig also sent a printed copy of the instructions as they appear on the website.  In my opinion, while adequate, the instructions need to be improved, and I understand from speaking with Craig that John Lucas and Mike Peace are providing suggested revisions – both of whom have also reviewed the jig.

 

I found the quality of materials to be good.  All machining was clean and assembly is simple, quick, and straightforward.  As shipped to me, the main Body of the jig was already assembled  as a unit – (#3 Cross Slide Lock, #4 Main Jig Body, #6 Cross Slide, and #7 Cross Slide Feedscrew).  All that was necessary at the point, was to thread the post into the female recess in the bottom of the cross slide. 

Next, install the Main Spindle by loosening the setscrew on the Spindle Hand Wheel, removing the hand wheel, and slipping the Main Spindle in to the Main Body of the jig and tightening the setscrew to retain the Main Spindle.  Then replace the Spindle Hand Wheel and tighten the setscrew.

I chose to use only the 16 tpi Main Spindle for my review due to lack of time.  Note that the each of the Main Spindles had a chuck nose already installed.  When ordering, you must specify which model of lathe you are using, as that will determine the post provided, as well as the thread sizing for the Chuck Nose.

 

Some mechanical issues could stand improvement.  The post screws into the Body of the jig, and a setscrew retains its position.  However, that setscrew tightens down on the male threads of the post without any form of cushion.  The purpose obviously is to prevent rotational movement during operation.  However, the use of a fiber plug would prevent permanent damage to the post threads.  This would be a simple fix.

 

As stated in the instructions, one mounts the collet and cutter in the headstock and secures the cutter with the draw bar.  While mounted in the chuck, screw on to the Chuck Nose, the male or female piece you intend to thread. 

The work is aligned with the cutter head by both advancing the Main Spindle left or right by use of the Spindle Hand Wheel, and by advancing the Body of the jig forward or backward by use of the Cross Slide Feed Screw. 

However, in order to advance the Body, one must loosen the Cross Slide Lock on top of the Body.  Doing so produces some play in the dovetailed Cross Slide, resulting in the work dropping slightly by force of gravity enough to make alignment a bit aggravating.  I am not a machinist, but tighter tolerances in the dovetail might correct this issue.  The double dovetail arrangement on the cross slide of the Baxter jig (similar on the Klein jig) probably provides more stability and may address the issue of having a bit of slop when positioning the jig to the cutter.  Not having those jigs available for comparison prevents a conclusion on this point.

 

One other mechanical issue involves the Main Spindle.  After the jig is set per the instructions, and everything is tight and ready for use, there still is play in the threaded Main Spindle.  It is possible to move the chuck nose back and forth – in other words, closer to the cutter or away from it.  I isolated the "play" to the fit of the Main Spindle in its threaded sleeve.  Without the chucked work on the jig, I could move the chuck nose .04".  That is significant as it is greater than the depth of the cut on a 16 tpi thread.  Again, in both the Baxter jig and the Klein jig, there is more mass in the threaded block in which the main spindle is situated.  This may address the "play" I found in the EZ Pro jig, although I do not know that to be true.

 

I did not experience any noticeable effect from this on the small sample piece done for this review.  However, much of the work I do that requires threads consists of larger urns that would extend as much as 12" from the jig.  I am concerned that extending a piece that far from the spindle could result in 2-3 times that amount of play, and may result in chatter, if not irregular threads.  For that reason, I elected to forego testing a hollow urn.  There would be too much work in time and materials to risk damage. 

I discussed this on the phone with Craig, and while we were talking, he checked a jig he had on his lathe.  He stated he did not observe any "play," and indicated the problem may be isolated to the spindle I was using.  The jig sent to me is a prototype of the new "Pro" model, and while he has not had any other reports of this issue, Craig intends to examine the spindle upon its return to determine the source of the problem.  Unfortunately, I did not use the other two spindles Craig provided and do not know if there was absence of play in those.

In fairness, it is unlikely I would use a threading jig for this purpose.  I turn most of my urns end grain, presenting an issue with unstable threads.  In addition, I use walnut, soft maple, cherry and those woods are not good choices for threading.  Using a better species, face grain, to produce a set of male/female threads used as an insert would be a preferable option, and well within the function of this jig.

The cutter cuts quickly and cleanly, and perhaps gravity would be sufficient to keep the work in proper contact with the spinning cutter.  However, I think I will let someone else test that theory.

 

Now, let's talk about the actual use of the jig!  The first step is to insert the jig in your banjo, and align the height of the jig with your spindle.  Set the stop collar (height setting ring) on the post.  Make sure you have tightened the Cross Slide Lock when doing this to take out the play in the slide.

This is a one-time setup.  When you remove the jig, you will leave the Body, Slide, Post, and ring in place as a unit.  I have provided two photographs from slightly different angles showing this process.

 

Prior to setting up the jig, I prepared face grain maple blanks - one each for the female threads and the male threads. 

 

The instructions state -

NOTE - A key measurement is to cut a tenon, which is approximately two millimeters larger than the threaded recess in the lid.

However, in hand chasing threads, I have always relied on the following chart, and sized my blanks by doubling the depth of cut – i.e., for 16 tpi threads, the male tenon would be .07" larger than the inside diameter of the female recess.

 

The instructions state to cut the female threads first, as it is somewhat easier to fit the male threads to the already cut female threads.  The photo below shows the cutting of the female threads.  As a note, I soaked both thread areas on the blanks with thin CA glue prior to threading them.

 

This is the appearance of the freshly cut female threads – very clean!

 

Next, I cut the male threads. 

 

I was not happy with the sharpness of the edges after the first pass, as I apparently did not position the work correctly.  I advanced the Cross Slide approximately ¼ turn and took a second pass.  Unfortunately, that was just a smidge too much and while the threads are very crisp, as one can see, they are slightly less than the diameter of the stock.  The result was a set of threads that was a bit loose when joined, though still functional.  I am certain that one would quickly attain proficiency in this process with a bit of practice.

 

Nonetheless, the overall result was positive!  The depth of field in these photos did not permit good focus on each threaded section, so I provided two photos.  Both sets of threads are crisp and clean, with no noticeable tear out.

 

CONCLUSION

As stated initially, I did not intend this to be a comparison review.  In short, the EZ Pro jig will perform as advertised and produce very well done threads.  It is a neat little product, and while lacking in some refinements available in other jigs, it is substantially less in cost.  However, Craig informs me that improvements to the jig have been made even since I received the model I reviewed.  In order to improve the alignment for depth process, they have changed the screw used on the cross slide to 1/4x20 and put index lines on the spindle knob.  They have also made the top aluminum knob, cross slide knob and the back spindle knob much larger, which makes them easier to control.  If one prefers a threading jig to avoid the learning curve and possible frustration of hand chasing, this jig should easily fill the bill!

© John Keeton 2013

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