Consew 756R (Seiko CH-8B) - Going back to 794H Needles???

[Smooooth]

Mechanics Question!!!!

My Consew 756R (Seiko CH-8B) originally came from the factory set up to use 794H (DYx3) needles which are 69.0 to 69.3mm in length. The machine had been modified (adjusted) to use 328 (DDx2) needles which are 60.6 to 61.2mm in length. Unsure of the reasoning why. Trying very hard no to overthink this, I should be able to raise the needle bar to its proper height for the 794H and that should be it, other than a full timing verification.  I am doing harness work and would really like to gain back that additional height.

Other than the availability of certain needle point styles - What might I be missing?

Thank you, Stephen

[brmax]

In one of my opinions I will say yes, with regards to the machine has been sewing great. 

With that its great to remove the cover plate and feed dog. Using this for your option to view the hook to needle alignment with its position. 

I cannot say what distance of needle lift past bottom center your machine is needed for spec..

 

good day 

Floyd

[Wizcrafts]

Your machine is basically the same class as a Cowboy CB4500. I own one and have adjusted the hook and needle timing several times.

Zero the stitch length lever first. Remove the System 328 needle and install a 794 needle. Loosen the needle bar clamping screws. Adjust the position of the needle bar to place the 794 (7x4) eye in the same vertical position relative to the hook as the 328, that the same distance up from BDC. The typical lift would be about 3/16" from BDC and the hook would intersect about 1/8 inch above the top of the eye. Fine tune as necessary to get the best pickup of the loop. You can test with thread to see if a decent loop in formed and if the hook picks it off in its midst. Lock down the needle bar screws when you have the best pickup at zero stitch length.

Hint: Keep the System 328 needles in case you have problems with needle deflection in some difficult project. In fact, get some in smaller numbers, like #19 and #20, for use with thinner thread, like #92. Shorter needles deflect less than longer ones of any given diameter. It should only take about 10 minutes to swap needle systems once you get the hang of it.

[Smooooth]

5 hours ago, Wizcrafts said:

Your machine is basically the same class as a Cowboy CB4500. I own one and have adjusted the hook and needle timing several times.

Zero the stitch length lever first. Remove the System 328 needle and install a 794 needle. Loosen the needle bar clamping screws. Adjust the position of the needle bar to place the 794 (7x4) eye in the same vertical position relative to the hook as the 328, that the same distance up from BDC. The typical lift would be about 3/16" from BDC and the hook would intersect about 1/8 inch above the top of the eye. Fine tune as necessary to get the best pickup of the loop. You can test with thread to see if a decent loop in formed and if the hook picks it off in its midst. Lock down the needle bar screws when you have the best pickup at zero stitch length.

Hint: Keep the System 328 needles in case you have problems with needle deflection in some difficult project. In fact, get some in smaller numbers, like #19 and #20, for use with thinner thread, like #92. Shorter needles deflect less than longer ones of any given diameter. It should only take about 10 minutes to swap needle systems once you get the hang of it.

Thank you!!!!!

Conversion today was successful.  Only Issue I am working around now is Forward and Reverse stitch lengths using the stops.  Had to slide the small bracket up on the stitch length selector to limit forward and balance it with reverse.  No big deal.  Did everything you mentioned and watched a Uwe video for a 441.  Good time for an in-depth cleaning. 

Added the Speed Reduction today, big difference.  Used some JB Weld to fill in the grooves on the Throat Plate and Feed Dog (extra set) to minimize markings, something I had been fighting with on some of the harness work.

This machine came out of the LL Bean R&D Lab.  Never used for production. 

All in all it has been a very good day. 

Thank you, Stephen