Fabric keeps sliding out of hoop

[LCG]

Hi, I downloaded a fantastic dragon from this site and tried to embroider it this evening. (I am very new to this). The fabric I used was a tweed/wool type fabric (not overly heavy).  It started of brilliantly, but when the stitch needed the needle to go left to right for a largish section, the fabric in the hoop was getting looser and looser and all the stitches become distorted so I had to stop the machine.  I tried it again on another fabric with a thin iron on stabilizer (which after reading your forum was probably too light weight), and again the fabric worked loose and it all went wrong.  

I wondered if anyone else has problems with the fabric working loose and how I can solve this problem.  I try and get the fabric as tight as I can in the hoop, but I can never get it 'drum tight' as it tells me to do in my machines instruction book.

Any suggestions for the best type of fabric I should use as a beginner so that I get some success.

Thanks

[LCG]

Hi, I think I have figured out why the fabric was being pulled out of the hoop, but what is this other problem.  Here is a photo of the back of the embroidery.  It is just lots of knots and bumps which were catching on the bed causing it to grab the fabric and pull out of the hoop. 

Why all the bumps at the back.  Is the tension too high/low or is it the thread I am using.  I am using 'gutterman' polyester thread.  

Any suggestions gratefully recieved.

20191230_193829.heic 20191230_193835.heic

[diver361]

What files you attached?

[Bear Embroidery]

What type of backing and needles are you using? I would suggest a doubled up soft backing. Use spray adhesive to stick 2 layers of it together and make sure it is generously larger than the hoop. Then spray the doubled up backing and place it on the back of your fabric. Make sure you are not hooping it so tight that the stitching creates a "spring" and lets your fabric move. Also, check your bobbin tension and upper tension by doing and H test and look for thirds.