Finally, after 2 years, I realized what these pieces are. LOL After ALL the frustration, I get rewards!!

Sir Steve, I got this saw for Christmas 2024 and they included both styles of the straight (pinless) blade adapters. Also included was a blade guard (for lack of a better term) but the instructions were a bit vague. But with your video help, i believe i can get them installed. Thank you sir, I am about to begin my journey into scroll saw art.

Just bought the 3921 and went ahead and ordered the upgrade parts from Wen linked here in the video description.  I wish I had checked the parts bag that came with the saw because it now includes the upgraded blade holders as well as two thumbscrews for clamping the straight blades.  No need to order the upgrade parts anymore.  Got mine from Amazon.

This saw has just been delivered to me today. I can't thank you enough for both of your videos about it. You're a hero!

I purchased the Wen 3921 directly from Wen and it arrived yesterday.  To my surprise it included the no-pin adapter that you show and it also included the 3920 adapter that you install in this video.  It also included the M4 16 screws with knobs on them.   There were no instructions for it, but thanks to your video I will know how to proceed.  Thanks for the great videos.

Thank you for an excellent demonstration - WEN should include a link to your video in every owners manual since they provide NO instructions on the adapter use or installation ( at least for the 3933)

This also works on the Harbor Freight scroll saw, with a slight tweak to the mounting hole. A file could be used. I used a taper reamer & only took 3 or 4 turns, by hand.
Finding a thumbscrew was another thing. I used a bolt with a wing nut cinched up tight to the head & secured with CA glue.
I want to see if the tension mechanism will work as well.
Maybe the table too.

Just received my new 3921 and it came with both the original "hanging" type adapters as well as the version shown here with thumbscrews already installed.

UPDATE:

WEN seems to have heard the criticism; the unit I just picked up includes 2x3920B-031 (the better holder) each with an easy to hand tighten screw (large wing-nut).  :)

VERY helpful, since the enclosed directions to do this were about as clear as mud. But the improved clamps were included which also had a real plastic adjustment knob top and bottom to facilitate the blade tightening process. I think if a groove gets worn in mine, I'll just braze on a little hard solder and grind it smooth and quench it to reharden it.

The 3922 comes with a thumb screw blade adapter.

Thank you sir! My saw will be delivered today. I bought two of these adapters and I’ll be immediately making a mold of it so I can replace them on demand.

I wrapped electrical conduit around the lighting arm and it did the job resonantly well the second upgrade I made was change the way the machine receives pinless blades,I swapped out the screw with the Allen wrench for a twisting locking mechanism and now I cut the blade changing time down from 5 minutes to one minute if you want to stop vibration from this machine put it on a stable base and you won’t have any vibration problem solved

For the life of me, I don't understand why it is so uncommon to find these blade adapters that don't have a thumb screw instead of requiring a tool. It would be so much better!

Ah, at last I get a chance to comment and thank you for your advice and tuition.  I am just starting with a scrollsaw I was given but have watched all your videos form years because they are so informative and enjoyable.  I reckon I will soon be upgrading my saw so your advice in the past will be very valuable when I look for a new one.
Many thanks, Brendan.

UPDATE. WEN is replacing the blade holder I used in this video with an improved version. It is supposed to fit better and come with a wing nut to tighten the clamp. It is still a couple of weeks from being ready to ship. 12/23/19. You can contact WEN at 847-429-9263 to preorder.

Very timely video. Just got this saw recently and it came with the alternate brackets, as well as large thumb screws to replace the hex bolts. However, the owner's manual did not mention them or indicate what they are for. Now I know. Thanks!

I just received my 3921 2 weeks ago from Amazon on sale and it came with these adapters. However it vibrated more. So I weighed the stock set at 13 grams and the adapter at 13.7 grams. I sanded .7 gram off each one and the balance was restored to previous minimum vibration. Some grease should be applied carefully to the threads only to increase life.

Thank you so much for this info.  I plan on ordering one today and this was so helpful and so well explained, especially for a newbie like me.  Again, thank you.

Been using this adaptive device shortly after purchasing this scroll saw.  Works very well.  Wore out the side set screw, but scew was easily replaced at local hardware store. Been using for about two years without any other problems.  With the "J" hook in the front, pin blades are easily used.