I recently got my first lathe, a HF 7x10. shimming the tooling was a giant pain so I broke down and got a steel OXA size QCTP. everything was going great setting it up until I got to the parting holder. this one is marked 250-007 and is the angled holder. I cant get the tool centered because it runs out of adjustment on the screw. I figured I might could turn it upside down but when I tried it just runs out of adjustment the other way. my question is am I thinking about this all wrong and I'm supposed to grind the blades down to fit or is there a way to adjust this that I am just missing? I am using the HF 1/2" blades that come in the HSS blank 5 pk. thanks for any help as this is driving me nuts.
-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
Quick Change Tool Post And Parting Tool Problem
- Thread starter Rebelathe
- Start date
- Joined
- Dec 20, 2012
- Messages
- 9,422
No, you are not supposed to grind the blade down. Once you set the blade extension for the minimum stickout you need for the job the vertical height adjustment should get you on center if the tool post is properly sized to the lathe. If you are running out of travel on the screw but have room to go lower maybe you can change to a longer screw?
Another option is to make a tool holder that holds the blade horizontally instead of at an angle. On a lathe your size, you can use 6061-T6 for the holder and it will work just fine.
Another option is to make a tool holder that holds the blade horizontally instead of at an angle. On a lathe your size, you can use 6061-T6 for the holder and it will work just fine.
- Joined
- Feb 1, 2015
- Messages
- 9,983
I expect that you can't drop the parting tool low enough. How much adjustment are you short? A possible solution is to mill or grind some material from the bottom of the parting tool holder. Another would be to grind your parting tool down to establish the correct height. A third option would be to position the QCTP so the parting tool holder hangs over the left side of the compound.
Of these, the latter is probably the easiest since there is no modification required but is also the most limiting as the compound has to be rotated to a position close to perpendicular to the spindle axis. Grinding the parting tool is probably next but will require a grinding operation on every parting tool that you buy.
Of these, the latter is probably the easiest since there is no modification required but is also the most limiting as the compound has to be rotated to a position close to perpendicular to the spindle axis. Grinding the parting tool is probably next but will require a grinding operation on every parting tool that you buy.
When you say 'runs out of adjustment', do you mean the tool holder itself bottoms out as low as it can go leaving the parting tool tip still too high relative to stock center? If so, by about how much is remaining? I've heard of this issue on certain import lathes where their compound sits abnormally high relative to 'typical' lathes of the same swing. So even though you purchase the recommended tooling set (250 series in your case) based nominal swing, all bets are off if the datum (top of compound) is sitting high because the tooling just stacks on top of that. The example I saw (cant recall exact model, Craftex or Busy Bee.. basically one of the rebranded import lathes) had this exact issue when swapping in a more modern adjustable tool post.
One guy was able to trim material off the toolholder bottom without sacrificing too much rigidity, but I don't recall if it was a parting holder. If you were 'pretty close' on tip height, say 0.1", you could notch out that from parting blade as long as its not a T-profile. This is not optimal at all though, loss of blade strength by reduced net height. Another option might be to get a straight shank insert type tool holder. hey inevitably will be thicker shank that what your toolholder will carry (example .75 or 1.0" shank vs say 0.625 toolblock gap). But what I've seen is people do is partially mill the tool shank to fit the lathe & correct the heiht issue correcting 2 problems in one shot. The good toolholders might be tough material, but the Asian knockoffs might be softer.
I'm not sure if this helpful, or your exact issue. IMO the tool holder suppliers should really provide a sizing sketch that correlates the vertical height from top of compound to lathe center & not rely on 'swing' which just confuses matters.
One guy was able to trim material off the toolholder bottom without sacrificing too much rigidity, but I don't recall if it was a parting holder. If you were 'pretty close' on tip height, say 0.1", you could notch out that from parting blade as long as its not a T-profile. This is not optimal at all though, loss of blade strength by reduced net height. Another option might be to get a straight shank insert type tool holder. hey inevitably will be thicker shank that what your toolholder will carry (example .75 or 1.0" shank vs say 0.625 toolblock gap). But what I've seen is people do is partially mill the tool shank to fit the lathe & correct the heiht issue correcting 2 problems in one shot. The good toolholders might be tough material, but the Asian knockoffs might be softer.
I'm not sure if this helpful, or your exact issue. IMO the tool holder suppliers should really provide a sizing sketch that correlates the vertical height from top of compound to lathe center & not rely on 'swing' which just confuses matters.
4
4GSR
Forum Guest
Register Today
Here's a part off tool that should work with the OXA tool post. Should be able to part off material up to 1.250" or 30mm in diameter.
http://www.banggood.com/MGEHR-1010-...MN200-Insert-Blade-For-2mm-Cut-p-1029279.html
Ken
http://www.banggood.com/MGEHR-1010-...MN200-Insert-Blade-For-2mm-Cut-p-1029279.html
Ken
Thank you all very much for the responses. my situation is like RJSAKOWSKI said. the tool holder bottoms out before I can get it low enough. it was probably around 1/8" or so from center when it stopped. I havent had a chance to measure any of it yet but it looks like if I milled enough off the bottom the holder would end up very thin. seems like a straight holder would solve this issue. I have seen people reference them as 250-007T but I am not able to locate them for sale. all my other tooling lined up perfectly so I dont think its a compound height issue relative to the whole post/set. this seems to be more of a design issue with this single holder style. its baffling since I see other people in threads and videos and such using the HF 7x lathes with seemingly these same chinese angled oxa size holders.
- Joined
- Mar 19, 2014
- Messages
- 2,682
- Joined
- Aug 15, 2013
- Messages
- 2,519
Hi Rebelathe,
Your problem is you have the wrong cutoff blade tool holder for your lathe. You're on the right track, you do need the one that holds the tool horizontal, 250-007T. I’m going to paraphrase an explanation from Littlemachineshop.com to save some brain cells. The part numbers referenced are LMS numbers. No affiliation, LMS just happens to be where I bought mine.
The two OXA tool holders (3117 and 3774) are the same except as follows:
The 3117 tool holder mounts the blade horizontally. Thus it can be used on lathes that have only 5/8” from the top of the compound to the centerline of the lathe, like the 7x mini lathes.
The 3774 tool holder mounts the blade at a 4 degree angle. It needs ¾” from the top of the compound to the centerline because of the angled cut off blade.
If you do buy from LMS, this is the one you want.
http://littlemachineshop.com/products/product_view.php?ProductID=3117&category=
Hope this helps.
Tom
Your problem is you have the wrong cutoff blade tool holder for your lathe. You're on the right track, you do need the one that holds the tool horizontal, 250-007T. I’m going to paraphrase an explanation from Littlemachineshop.com to save some brain cells. The part numbers referenced are LMS numbers. No affiliation, LMS just happens to be where I bought mine.
The two OXA tool holders (3117 and 3774) are the same except as follows:
The 3117 tool holder mounts the blade horizontally. Thus it can be used on lathes that have only 5/8” from the top of the compound to the centerline of the lathe, like the 7x mini lathes.
The 3774 tool holder mounts the blade at a 4 degree angle. It needs ¾” from the top of the compound to the centerline because of the angled cut off blade.
If you do buy from LMS, this is the one you want.
http://littlemachineshop.com/products/product_view.php?ProductID=3117&category=
Hope this helps.
Tom
That does help tremendously. not only helped find the holder I need but reassured me I wasnt a complete idiot just missing something simple. I dont feel nearly as bad knowing the holder I have just isnt correct. thanks again for all the help.