Ihave a doall saw model c430a the head will just drop into the piece with no reason

Contact the maker for this issue. It is industrial equipment.

C-305A Instruction M anual - DoAll Sawing Products

https://www.doallsaws.com > manuals > C-305A 6...

PDF Be sure to provide machine model and serial numbers with any correspondence or parts orders. Specifications contained herein were in effect at the time this ...

C-305A Parts M anual - DoAll Sawing Products

https://www.doallsaws.com > manuals > C-305A 6...

PDF PARTS MANUAL INDEX. 6/14. Fiche No. E-145 Model C-305A Serial No. 607-13101 to. _. PAGE NO. DESCRIPTION. FIRST SERIAL. LAST SERIAL PAGES.

There must be a switch or sensor that knows when it has completed the cut. That’s where I would start.it cuts out because it thinks it is finished for some reason.

Consult your manual. If you don't have the manual , check bandsawmanuals.com ,they have free downloadable manuals.

There's a free downloadable manual on bandsawmanuals.com . I have downloaded manual from them

I saw a video on youtube about Doall Band saw transmission. If you have time, watch it, and if you need parts, you check bandsawparts.com

Contact Doall or you may also download manual on bandsawmanuals.com

If it had stopped cutting and won't turn on again, it sounds like the problem is with the motor of the band saw. I suggest you contact Doall or if you have vast electrical knowledge, open the motor and check yourself which part of it have failed.

What is the model of your band saw? Try to visit this site metalsaw.com . They offer band saw repair services.

i have a great company for you to contact to find the perfect blade for your needs. go to www.doall.com and click on the doall sawing tab and find the customer support phone number. call them during business hours and you can get at blade tech on the phone that will ask you a few questions to what saw you have and what your cutting and they can put you on the perfect blade. i use them for a bandsaw we use at work, we manufacture awnings and signs. i get all my bandsaw blades from Doall

I used to work for Doall saw company. While I am not familiar with the particular model you have, I have seen issues like it in Doall saws.
Firstly, If bearing guides are not adjustable, replace them. There should be only about a 32 of an inch play between them (in addition to the thickness of the blade). Secondly, for a prodution horizontal bandsaw you should have the blade tensioned a @30,000 psi. Thirdly, if after that, you are still having problems, I would suggest checking the bearings on your drive and idler wheels for runout (in addition to the condition of the tires).