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| raynerd:
--- Quote ---well you don't seem to have understood it very well cos most of what you wrote is wrong --- End quote --- Correct Darren, I must not have understood because I can`t find anything that explains why you bored in the main shaft off centre and anything stating why you have no dovetails on the front face in addition to the side. You do mention something about your compound slide being high but I don`t see how this effects having a front face for tool holding as well as the side. You do discuss in a little detail the issue of the dovetail angle but not that I understand it. However that said, I think with NickG explanation I understand a little more why 45deg dovetails would allow more error. So, sorry, I have read and even printed this thread out and I can see you are unwilling as most would be to retype info already printed, but I just can`t find it and would really like to know! No doubt you will be able to embarrass me and quote your posts where the info I require is printed but if it is there, I obviously don`t understand. Sorry, Chris Cheers NickG - if you have time for something on CAD it would be useful! |
| Darren:
Chris I am not unwilling at all, it's just that it seems you have not read the thread and it could answer most of your questions? Here goes then... --- Quote from: craynerd on September 06, 2009, 08:23:48 PM ---Hey Darren, I`ve viewed this topic many times over the last few weeks as I have been concentrating on my workshop and machines and getting everything running as I want it before I go any further with engine builds etc. I have decided to make a QCTP like this and just have a couple of questions. I`m going to be using a round bar of steel rather than a block like you did, only because that is the scrap I found and was given free from the scrap heap! --- End quote --- I didn't use a block, I cut a section from a round pin --- Quote from: craynerd on September 06, 2009, 08:23:48 PM ---1. Can I ask about your off centre bore in the main body of the tool post, was this simply to give more clearence when the two sides where taken down to size? I guess if it had been central, once the centre spigot and cam were fitted it would have got near to the edge of the dovetails/sides right? --- End quote --- My round bar was not big enough for two dovetails (you don't need two anyway) and I gained more clearance for machining by offsetting the mounting hole --- Quote from: craynerd on September 06, 2009, 08:23:48 PM ---2. Also, most QCTP have two sides each dovetailed to accept a holder when needed for turning or facing, so a side on the left and a side on the front. I noticed that you have cut flats on two sides but only dovetailed one. Is there any reason you didn`t put a dovetail on the second side so as to gain to working faces? --- End quote --- Explained above --- Quote from: craynerd on September 06, 2009, 08:23:48 PM ---3. The dovetails themselfs are 60deg or did you use 55deg because of your cutting tool - either way, I mentioned a 60deg dovetail in my latest thread here: http://madmodder.net/index.php?topic=1731.msg17115#new and Jonny gave a reason why it may be more suitable to use 45deg dovetails. I`ll be honest that I`m still not 100% sure why I would have to be more accurate cutting 60deg dovetails than 45deg dovetails but if this is the case, do you think the 45deg would be more suitable? --- End quote --- I didn't use 55deg dovetails, I made 60deg ones....it's in the text. --- Quote from: craynerd on September 06, 2009, 08:23:48 PM ---Anyway, hope you can help. I wasn`t a member on here when you posted this thread so just wanted to say nice job and hope mine turns out as well. I`d be chuffed if it did! --- End quote --- Hope that help Chris.... :thumbup: |
| NickG:
Chris, I can't see the advantage of having 2 dovetails either, you can just swing it around the other way if you really need to and turn the tool round in its holder. Nick |
| raynerd:
:thumbup: :thumbup: :thumbup: :thumbup: Cheers Darren, I know I`m a pain in the ars3 but you`ve helped a lot. I think the biggest reason I looked a t1t is because I said, "I`m going to be using a round bar of steel rather than a block like you did,...! " I said it the wrong way around, I have a block and I know you used round - sorry, that probably did look daft! I know that you don`t need both front and side faces machined to accept a tool holder but it is a little more convienient. I guess I need to plan out and see what layout is best. I`m still not totally clear about the 45deg V 60deg dovetails but I guess it seems that 45deg would be better/easier. I was actually looking at the QRTP sold by RDG and the clamping mechanism is quite strange - it isn`t just a straight dovetail. Anyhow, perhaps it is time to get this talking into swarf! Arc Euro actually has some dimension shown for their QCTP so I may use those. Thanks again, and sorry for being a pain. Chris :headbang: |
| NickG:
Chris, haven't had a chance to do the CAD sketch to explain yet but I will. A picture is worth 1000 words in this case. I still don't see how it's any better with 2 on really, you wouldn't leave 2 tools on as they'd prob get in the way. The RDG ones are dickinson style posts, it's not really a dove tail, bit more like a T slot and the cam pulls a T back towards the main block pulling the T slotted holder with it and clamping against the block. Not sure if these are better or piston type? 6 & 2 3's ? Nick |
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