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| Another new project... a QCTP (Quick Change Toolpost) |
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| AdeV:
--- Quote from: andyf on August 13, 2010, 07:13:47 PM --- It probably started life more this sort of shape, so its shank could be set parallel to the lathe's axis, but repeated sharpening has removed the part outlined in red. I think it's time to raid the piggy bank and treat yourself to a new one. --- End quote --- Thanks Andy - that certainly makes more sense than the tool being the shape it is from new... I'll waste no more oilstone on it :D Damn, I just put in an order with Chronos.... but OTOH it looks like RDG have some nice boring bars... so... 16mm or 20mm...? |
| Ned Ludd:
Hi AdeV, Nine hours boring, that must have been truly boring. :lol: I do think you have to revise your methods and quickly. I was going make a recommendation for a tip, but on looking at current on-line catalogues for Iscar and Sumitomo, the ones I use are not to be found, curse this craze for modernizing everything. Anyway, the ones I would have recommended are truly magnificent. They allow a near chrome like finish, even with very small depth of cut, on all the metals that I use. I shall have to be careful with my remaining stock, as replacing them might prove difficult. :( :( Ned |
| AdeV:
--- Quote from: Ned Ludd on August 13, 2010, 10:14:37 PM ---Hi AdeV, Nine hours boring, that must have been truly boring. :lol: I do think you have to revise your methods and quickly. --- End quote --- The main reason it's taken so long, other than the general lack of time/day I have at the machines, is the smallness & slowness of the cut I have to take with the boring bar, plus the frequent requirement to stop & clear out chips. For example, I absolutely dare not push it past a 0.020" cut, at quite a slow feed rate (my lathe quotes 160cuts/inch, whatever that works out to in thou per revolution). I started at 190rpm, but was down to 112rpm by the time I was out at the quoted diameter, simply due to the heat being generated by the cutter bit... I can only take so much cutting oil smoke. At least 45 mins, maybe 1hr, was spent facing the back face of the cut, as best I could, with the bar over at an angle, I can't get right to the corner of a cut as previously mentioned, so the bottom of the hole tended to form a bowl shape. Then you have to factor in some time to re-arrange the tooling in the toolpost (+ I got some extra shims to bring the tool to absolutely smack on centre height, it was a smidge below when I started). So add 1/2 to 1 hour for that... and before you know it, you've got 9 hours invested in the piece. Hence my internal debate about going to the full 3" or not: It's not essential, so I don't think I will. Instead, I'll turn the extra off the S/S bar I have. I have some carbide tipped turning tools, so I should be able to attack the cut quicker than boring out the hole.... --- Quote --- I was going make a recommendation for a tip, but on looking at current on-line catalogues for Iscar and Sumitomo, the ones I use are not to be found, curse this craze for modernizing everything. Anyway, the ones I would have recommended are truly magnificent. They allow a near chrome like finish, even with very small depth of cut, on all the metals that I use. I shall have to be careful with my remaining stock, as replacing them might prove difficult. :( :( --- End quote --- How about a photo? And maybe the tip type? :) |
| madjackghengis:
Hi AdeV, the easy way is to put a torch to your boring bar, remove the small piece of carbide, and replace it with a much larger one, which you can grind to match the picture you show of Andy's suggestion. The long way is to get a boring bar that takes inserts, as it will cut better, and will have good chip control, something difficult to accomplish with the plain brazed bar. Good chip control can double or triple your boring speed if the edge is right. The one I use most has a TPG insert, and gives a good finish, and empties the cavity pretty well when there's room. :thumbup: mad jack |
| AdeV:
--- Quote from: madjackghengis on August 14, 2010, 09:13:19 AM ---Hi AdeV, the easy way is to put a torch to your boring bar, remove the small piece of carbide, and replace it with a much larger one, which you can grind to match the picture you show of Andy's suggestion. The long way is to get a boring bar that takes inserts, as it will cut better, and will have good chip control, something difficult to accomplish with the plain brazed bar. Good chip control can double or triple your boring speed if the edge is right. The one I use most has a TPG insert, and gives a good finish, and empties the cavity pretty well when there's room. :thumbup: mad jack --- End quote --- Hi Jack - that boring bar is plain HSS! No carbide in sight... I'm going to order a couple of indexable boring bars - a big one for big holes & a small one for, well, I'm sure you get the idea :) RDG do a fine looking selection all the way up to 20mm... |
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