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Cutting threads on Craftex CX701 lathe

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  • danlb
    replied
    Originally posted by BCRider View Post
    What I find odd is that the CAB knobs that I took to be a more fully functional quick change box are in reality just 2:1 division gears. Most of the selection of the threads to be cut are made with the change wheels and then the correct multiple is selected with the front box controls..... odd that.
    Yes it is odd, but it's odd in a useful way for a hobbyist. The C-A-B positions give you three threads that cover a very wide range. If you chose to install the gears for 8 TPI, for instance, then you get a choice of 8, 16 or 32 TPI without changing the gears again. You can leverage this if you are designing your own parts by choosing to use only those 3 TPIs in your design.

    My lathe has a QCGB that gives 9 different threads per gear setup, but they are sequential, so I get 8 -> 14, or 16 -> 28 or 32 -> 58. That means that if I am to cut one of the three most common threads for small screws (10, 16 or 32) there's a good chance that I will not have the right gears set up.

    Dan

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  • brian Rupnow
    replied
    BCRider--What does one do when one has a no good first hand knowledge of the process except from an apprenticeship from 50 years ago, a really really crappy owners manual, and no close machinist friend that he can call over to your place for help?--Exactly what I've been doing the last few days. Watch you-tube videos of threading (some of which are blatantly incorrect), ask the opinion of folks on the forum and hope you don't get smart assed answers, dig around and find old posts on the same issues, and download/read some of the 100 plus "tutorials" from the internet. Thank you to all who have helped with my questions---Brian.-

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  • BCRider
    replied
    The lathe will cut both. It's not a metric or an imperial only.

    It took me a few minutes looking at the chart but suddenly the light went on.

    The H's and odd numbers are the spacer or gears intended to stack on the intermediary pilot shafts. The vertical lines in the gear number blocks in the tables indicate which gears are to be in mesh with each other between the stacks.

    The set of gears should one for each of the different numbers you see in those configuration boxes.

    By rights the lathe is set up for imperial threading. So it works with the indicator and allows you to engage and disengage the half nuts as per normal practice for the pitch of the thread being cut.

    With the right gearing given in the chart in the gear configurations you can get a lot of the metric equivalents. Note however that like with most lathes set up primarily for imperial sizes that when doing metric you must engage the half nuts and leave them engaged for the whole threading operation when doing metric. This is spelled out in the section on threading.

    What I find odd is that the CAB knobs that I took to be a more fully functional quick change box are in reality just 2:1 division gears. Most of the selection of the threads to be cut are made with the change wheels and then the correct multiple is selected with the front box controls..... odd that.

    Some of this is already pointed out but I hope my post fills in some points that seem to have been missed.

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  • EddyCurr
    replied
    Originally posted by ecortech View Post
    H indicates spacer
    8tpi according to the chart
    Z2=80 on top shaft by itself.
    80 tooth meshes with Z3 40 tooth on the second shaft.
    Z4=30 tooth on the same shaft as Z3.
    Z4 meshes with L=60 tooth
    L-60 tooth on the bottom shaft
    Lever on front in the C position

    Ed
    Originally posted by Drifter1885 View Post
    Thanks, that is what I finally ended up doing, set it all the way the chart reads, did a very light cut and it was 36tpi.......and yet when I set it to 'B' or 'C' it cut correctly....I am engaging the half nut at 4. Is that correct? Couldn't find anything in the manual on that.
    Not a great example to drag out of the crypt.

    The OP's first post shows that he is misreading the Gear Chart.

    ecortech's post shows the correct gear configuration, but the
    wrong lever position (pos C gives 32TPI, ecortech should have
    said pos B for 8TPI). Next, the OP mistakenly reports that he
    gets 36TPI and then says it cuts correctly when he set it to
    "B" or "C".

    Not surprisingly, the thread goes off-topic as people pile on
    with their inputs.

    Sheeeessh.

    .
    Last edited by EddyCurr; 05-28-2016, 07:34 PM.

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  • brian Rupnow
    replied
    I found this while threshing around on the internet looking for threading info. Good info here. Thanks Black_Moons.

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  • Black_Moons
    replied
    Originally posted by David Powell View Post
    Offshore machines . built for the hobby and light industrial market, are a gamble. Their makers do not have, never have had, and probably never will have good reputations to maintain. You may get a good one, or you may not. I just gave away my 12 by 37 Busy Bee machine. I am keeping my Colchester and Southbend lathes. The Busy Bee lathe made me some money and built some parts for my models but I never really liked it, and never got it to turn as truely as I would have liked. regards David Powell.
    Eh I don't mind mine, other then the fact you pretty much have to change the change gears if you ever do any imperial threads as they all require different change gears (most of the metric ones do not (uses common gears + CQGB), dispite it being an imperial leadscrew)

    Kinda funny for a QCGB machine... QCGB really only helps to adjust feed rates quickly.

    Leave a comment:


  • David Powell
    replied
    Maybe, just maybe, now some of you will realise---

    Originally posted by Black_Moons View Post
    Come to think of it, my busy bee lathe (12x36 with QCGB) has a casting fault in the QCGB as well. It lacks a portion of the casting around one of the roll pins used to align the face of the QCGB, so it pissed oil everywhere.

    I took it apart, filled the roll pin an area with permatex orange gasket maker or somesuch stuff, then assembled it, waited 24 hours and filled.

    So far, Nothing has leaked out that roll pin that is now filled with gasket maker.. :P
    Offshore machines . built for the hobby and light industrial market, are a gamble. Their makers do not have, never have had, and probably never will have good reputations to maintain. You may get a good one, or you may not. I just gave away my 12 by 37 Busy Bee machine. I am keeping my Colchester and Southbend lathes. The Busy Bee lathe made me some money and built some parts for my models but I never really liked it, and never got it to turn as truely as I would have liked. regards David Powell.

    Leave a comment:


  • Black_Moons
    replied
    Originally posted by Drifter1885 View Post
    I have not had a good experience, overall, with this lathe. at approximately 10 hours, the gearbox self-destructed, BB did not want to cover it. I posted pics on here, asking for advice, these are a great bunch on here. I forwarded some of their ideas/advice as to what had gone wrong, BB still would not cover it. It is a 14-16 hour drive to the nearest location; I would have, if withing range, taken it to their outlet and set it right in front of the door with a copy of the transcripts to hand out to whoever wanted to read BB's comments on it. FINALLY they went for the parts, took around a year or so to get the parts, then it was up to me to rebuild it. And what did I find?...the original gear box had been cast wrong, resulting in the manufacturer having to machine the support boss in side dangerously thin, which resulted in the failure. Even after rebuilding it, it still has a noise inside, but not finding any cuttings in the gear box.
    Come to think of it, my busy bee lathe (12x36 with QCGB) has a casting fault in the QCGB as well. It lacks a portion of the casting around one of the roll pins used to align the face of the QCGB, so it pissed oil everywhere.

    I took it apart, filled the roll pin an area with permatex orange gasket maker or somesuch stuff, then assembled it, waited 24 hours and filled.

    So far, Nothing has leaked out that roll pin that is now filled with gasket maker.. :P

    Leave a comment:


  • Paul Alciatore
    replied
    That was my impression after looking at the charts in the manual. Perhaps it explains the problems everyone here seems to be having. The first thing to do with this lathe is to determine if you have an English or metric lead screw. And then use the appropriate chart.

    But there may be more problems after that.

    Makes you wonder if the designers ever actually used it.



    Originally posted by Lew Hartswick View Post
    It looks like there are two versions of the lathe, Metric and inch . The chart on the right is for an inch lead screw and the other for a metric one.
    Am I close? :-)
    ...lew...

    Leave a comment:


  • Drifter1885
    replied
    Originally posted by brian Rupnow View Post
    I too am interested in the answers you get here. I have the same lathe, and the information provided with it is just terrible. I do however, really like the lathe.---Brian
    I have not had a good experience, overall, with this lathe. at approximately 10 hours, the gearbox self-destructed, BB did not want to cover it. I posted pics on here, asking for advice, these are a great bunch on here. I forwarded some of their ideas/advice as to what had gone wrong, BB still would not cover it. It is a 14-16 hour drive to the nearest location; I would have, if withing range, taken it to their outlet and set it right in front of the door with a copy of the transcripts to hand out to whoever wanted to read BB's comments on it. FINALLY they went for the parts, took around a year or so to get the parts, then it was up to me to rebuild it. And what did I find?...the original gear box had been cast wrong, resulting in the manufacturer having to machine the support boss in side dangerously thin, which resulted in the failure. Even after rebuilding it, it still has a noise inside, but not finding any cuttings in the gear box.

    That is a quick run down on the issues I've had with mine. As to cutting threads, that too has been a bit of an issue; the manual is very inadequate; all I can find on the half-nut is, once engaged, do not disengage until that thread cutting procedure is finished. From what I've read elsewhere, you can disengage it as long as you engage it on the correct number, but don't know for sure.

    So today, I need to make another bushing; I need a 3/4"by 16tpi on the inside, and 1"by 8tpi on the outside. I used a 3/4"x16 tpi nut and turned it down to 1" on the outside, then set it up for threading, but can't seem to get it to cut 8tpi with the gear/speed selection in the chart. So back to playing......

    Leave a comment:


  • Lew Hartswick
    replied
    It looks like there are two versions of the lathe, Metric and inch . The chart on the right is for an inch lead screw and the other for a metric one.
    Am I close? :-)
    ...lew...

    Leave a comment:


  • brian Rupnow
    replied
    I too am interested in the answers you get here. I have the same lathe, and the information provided with it is just terrible. I do however, really like the lathe.---Brian

    Leave a comment:


  • Drifter1885
    replied
    Thanks, that is what I finally ended up doing, set it all the way the chart reads, did a very light cut and it was 36tpi.......and yet when I set it to 'B' or 'C' it cut correctly....I am engaging the half nut at 4. Is that correct? Couldn't find anything in the manual on that.

    Leave a comment:


  • ecortech
    replied
    H indicates spacer
    8tpi according to the chart
    Z2=80 on top shaft by itself.
    80 tooth meshes with Z3 40 tooth on the second shaft.
    Z4=30 tooth on the same shaft as Z3.
    Z4 meshes with L=60 tooth
    L-60 tooth on the bottom shaft
    Lever on front in the C position

    Ed

    Leave a comment:


  • Black_Moons
    replied
    the gears don't engage correctly on my lathe either if used as the gear change chart says.

    Says something like 24 tooth and 48 tooth, Well those don't mate when reversed due to spacing or somesuch, Ended up moving to a 20 and 40 tooth gear (included with the set) instead, its the ratio that is important not the tooth count.

    I am guessing H indicators where the spacer should go. I would wager the | lines indicate what gears mesh.

    Leave a comment:

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