I would like to know what thread everyone uses to machine piece with. I have read that the thickness of your thread can cause your 1/4 seams to
be off.

Beverly

I like using Coats or Gutterman's all-cotton thread, if it's an all-cotton top that I'm piecing. I do this so the strength of the thread matches the strength of the fabric. Not sure that it's necessary, but that's what I've liked over the last few years.

The thread thickness can throw off your 1/4" seam ... you can adjust by doing a scant 1/4" if your thread is really thick.

But, the more important thing is that you are consistent throughout the blocks and all the piecing. That's what will get your seams to match.

It's another good reason to do a couple of sample blocks ... you can adjust your seams if the block size you're ending up with isn't quite right. And yet another 'but' - still won't matter if you're consistent with the seams for that top!

I like Superior Thread. I sue MasterPiece for the top and Bottom Line for the bobbin.

www.superiorthreads.com

I use thread from Connecting Threads. It has always worked great for me.

I also use superior thread and a very small (Micro) needle size. Both help keep my 1/4 inch seam accurate.

I love the thread from Connecting Threads. It is really good thread and there is so much on a spool. I have put together 4 lap quilts from one spool. There is little to no lint. LOVE IT.

I use Connecting Threads Essentials, great price and a lot of thread on a spool.

I also use the thread from Connecting Threads.
It DOES have lots of thread on a spool.
And I love how it sews! :D

Is it OK to use polyester thread for piecing my blocks together. I heard that polyester thread is not good for the quilting process but is it bad for the block piecing process?

That is true but also it is the thickness of the fabric too.
If you are not getting a perfect 1/4 in seam then do a scant 1/4 in seam if you have needle positions on your machine.
every fabric even with the same thread will be slightly different....
I just use a good cotton thread NO polyester thread.