Sometimes for that to work reliably you need to do a binary COPY.

As a test, can you save the file you want to print, then from a CMD window:

COPY {MyPrintJobFile} LPT3 /B

>Hi, Al, thanks for your answer
>
>Perhpas I should have added it is not printer doesn't print.
>
>When I send from the server prints draft and on cols and rows
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>When I send from a workstation prints using driver and feeds a couple of pages and doesn't respect cols and rows
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>Since they are using a system of mine in Clipper I use NET USE LPT3... but with a batch file throught COMMAND.COM every time PC boots
>
>Unless you mean using CMD I'll be able to skip driver that's not the solution.
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>>>Hi friends
>>>
>>>I was happy when I got a matricial printer did what I wanted it to do with this instructions
>>>
>>>SET PRINTER TO FILE file.txt
>>>
>>>@ n,n say 'something'
>>>
>>>SET PRINTER TO
>>>
>>>COPY FILE file.txt TO LPTn.DOS
>>>
>>>And I drawed a winning smile at my client: Do yo want to star using my new system? Because I tested and worked fine.
>>>
>>>But when I did the first test in a net PC which doesn't have the printer directly connected, matricial printer bursted out laughing.
>>>
>>>Does anyone know any other great trick?
>>
>>Assuming the printer is connected to a computer "ServerName", and it's available using a share name "MatrixPrinter", then on your workstation you can redirect your LPTn printer port to that share:
>>

>>REM From a CMD prompt run
>>NET USE LPTn \\ServerName\MatrixPrinter /persistent:y
>>

>>Also, depending on how print jobs are spooled you may notice a 15 second delay between your COPY command and the start of the print job. This can be reduced by adjusting a registry key LPT_timeout: https://technet.microsoft.com/en-us/library/cc959496.aspx . These days, with fast computers 2 seconds is probably a safe value.