What lathe tool for deburring holes?

I use a long half inch square toolbit mounted in a Dickson toolholder ,the tool protrudes out each end of the tool holder ,one end is ground with a 45 degree angle plus some top rake so that it will chamfer say the end of a bar from a tiny chamfer up to a large chamfer, the other end of the tool bit is ground with a 45 degree chamfer plus top rake and with lots of front clearance similar to a boring bar so that it will again produce a fine chamfer or a large one. the tool is a permant fixture in the tool holder , to cut internal or internal chamfers all that is required is to rotate the main tool holding block through 90 dergrees,or just change the position of the tool holder. this works well and will deal with most materials including brass on my Colchester.For the Myford I have have a similar set up with a long 5/16 square tool bit though I find that the top rake does not cope with brass so well so I also have a zero rake similar tool. when instrument making usual shop practice was to use a M&W 3 cornered triangular scraper for bores, mainly in brass turning, and a very fine 6 inch file for taking the edge off external corners ,sometimes a graver would be used if a sharper profile chamfer was required , personally I found the M &W scraper a bit too large ,so made a finer scraper from a 4 inch triangular file with a turned up wooden handle,60 years later I still have it. The long toolbit chamfer tool was not my idea,I found one in a box of tools donated to me,the property of a deceased toolmaker,its in constant use and have the Dickson holder visiblaly marked so that I can grab it quickly.

When i started this thread i suppose i was looking more for a tool for 45 degree chamfering rather than deburring

anyway after all your thoughts i bought this tool from chesterfield machine tools on eBay....it works a treat and can do perhaps a 3mm internal chamfor.and much larger external chamfor

Does not look like it gives a 45deg chamfer to me unless you were to mount the holder at an angle?

Something more like this that holds square inserts at 45deg would give what you say you wanted