Line boring machine help

FMKWELDING · Jul 7, 2017

So I built my own machine. This is my second and I thought I had the bugs worked out from the first one. Well that's a big no. Anyway the trouble I am encountering is the feed screw set up. I have a Bridgeport type servo feed connected via a love joy coupling. Goes through a bearing which is set screwed to the all thread so that it can push and pull drill motor. Now the issue is the all thread which is 5/8-18 I think B7 is stripping. I had this issue before buthe this time I used a tacked nut on both side of the plate. Today it stripped to the point that it stopped the servo and stripped a gear in it. I need something that can handle repeated trips back and forth and typically within the same 3 to 4 inches all the time. I am open to any suggestions you may have. I used 5/8-18 because I felt it needed to be that slow of a pitch because I am already at about slow as the servo feed will go? Will have pictures asap

FMKWELDING · Jul 7, 2017

https://mail.aol.com/webmail/getPar...=1&scope=STANDARD&saveAs=20170707_184827.jpeg

IronReb · Jul 7, 2017

FMKWELDING said:
https://mail.aol.com/webmail/getPar...=1&scope=STANDARD&saveAs=20170707_184827.jpeg

Link will not open for me? Ask for AOL login

IronReb · Jul 7, 2017

Switch to an ACME nut and screw, last machine I used had what I think was 3/4-6 acme to feed the motor back and forth.

Quick google....Great deals from imsrv | eBay Stores

If you could get some gear reduction via small chain and sprockets your power feed would be much smoother and happier.

FMKWELDING · Jul 7, 2017

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FMKWELDING · Jul 7, 2017

DDoug · Jul 7, 2017

FMKWELDING said:
I need something that can handle repeated trips back and forth and typically within the same 3 to 4 inches all the time. I am open to any suggestions you may have. I used 5/8-18 because I felt it needed to be that slow of a pitch because I am already at about slow as the servo feed will go? Will have pictures asap

You need acme thread as suggested above for the wear, and you need to sit down with paper & pencil and figure out your federate desired, along with keeping the feed motor in the middle of it's speed range.

FMKWELDING · Jul 7, 2017

digger doug said:
You need acme thread as suggested above for the wear, and you need to sit down with paper & pencil and figure out your federate desired, along with keeping the feed motor in the middle of it's speed range.

Well that's where I'm lost at. With the 5/8-18 taking a.030 depth of cut I am running the feed just above where it starts at. Meaning if I slow it down much more it just stops. So I don't know that going with a coarser thread is going to fix anything besides the wear issue. This is on a hole that finished at 2.768" the feed speed will need to go slower as the hole gets bigger( future jobs) . Unless there is a way to slow down my feed internally not sure about that. The units like mine that are manufactured have a coarser thread than mine, not sure what pitch but by the pictures they're coarser looking anyway I'm not sure how they are over coming feed speed.

IronReb · Jul 7, 2017

FMKWELDING said:
Well that's where I'm lost at. With the 5/8-18 taking a.030 depth of cut I am running the feed just above where it starts at. Meaning if I slow it down much more it just stops. So I don't know that going with a coarser thread is going to fix anything besides the wear issue. This is on a hole that finished at 2.768" the feed speed will need to go slower as the hole gets bigger( future jobs) . Unless there is a way to slow down my feed internally not sure about that. The units like mine that are manufactured have a coarser thread than mine, not sure what pitch but by the pictures they're coarser looking anyway I'm not sure how they are over coming feed speed.

Maybe make an bracket to bolt the power feed to.
Use a jack shaft from the feed unit that has a small gear or sprocket connected to a larger gear or sprocket on the lead screw

Hbjj · Jul 7, 2017

+1 on the acme and more gear reduction
But it sounds like you have something in a bind 2.7ish and .03 doc really isn't much
Can you take the feed off and run it by hand should only take finger pressure to make it cut

FMKWELDING · Jul 8, 2017

I understand the gear reduction to slow feed. Maybe I am babying it to much. Here is a picture of the unit I copied mostly because I am cheap and I already had the drill and feed. The picture of my unit was after the stripping issue I had yesterday. I was able to remove one nut and shorten the all thread. There was another nut on the opposite side of the plate . Maybe after running it for a bit they were no longer in time and fighting each other.

After cutting the one nut off yes it can be fed by hand. Could I stay with the fine thread and go with a longer nut? Like a coupling nut and avoid the stripping issue?

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Hbjj · Jul 8, 2017

IMHO a longer nut won't help
V threads really arnt for transmitting motion
Acme or a ball screw is
I have a shop built line bore set up it uses a ball screw and alot of gear reduction

FMKWELDING · Jul 8, 2017

Acme it is then. Closest I can find is 5/8-10. I can get a brass or steel nut for it. Yeah your set up is what I am used to running. I've been around b&d and mactech so using the set up I have built has been a little frustrating to get going but.... if I had the money I would get what I want. Currently I don't have a lot of this work lined up but hope to get more so I need to get the bugs worked out.

Illinoyance · Jul 8, 2017

The nut should be BRONZE or steel. Make provision for lubricating the nut.

Peter from Holland · Jul 8, 2017

Illinoyance said:
The nut should be BRONZE or steel. Make provision for lubricating the nut.

I agree Use a good quality threaded rod Not galvanized And make it so you can replace it with a new one regulary
Perhaps use some treaded rod with a even finer pitch If you really want to go fancy make a nut in 2 halves that you can clamp So you don`t need to go reverse (at high speed off coarse ) and more fancy use a hardened ground threaded rod
You could also use a special nut that you can turn a bit lengtwise and you freely can advance the nut over the rod
Turn it back and it is engaging again
Basicly it is a hole with threading and you bore another hole at a slight angle leaving half threads on one side at the bottem and on the oppisite side at the top Very clear isnt it

Peter

FMKWELDING · Jul 8, 2017

Thanks guys. Yes I meant bronze. I'm assuming the other setups that work the way mine do are ran a little more aggressively than I have been running mine. Watched a few videos on YouTube and guys are really hogging the metal out.

IronReb · Jul 8, 2017

After looking at your setup...that servo hooked direct to the 5/8 acme will not be so much different than the way a milling machine works thrust wise.

Build a good setup that has nothing binding and smear some oil on it from time to time and it will out last you.

triumph406 · Jul 8, 2017

Illinoyance said:
The nut should be BRONZE or steel. Make provision for lubricating the nut.

cast iron instead of steel I would think.

DDoug · Jul 8, 2017

IronReb said:
After looking at your setup...that servo hooked direct to the 5/8 acme will not be so much different than the way a milling machine works thrust wise.

Build a good setup that has nothing binding and smear some oil on it from time to time and it will out last you.

Yes, just rob a Bridgeport, you've already got the feed motor, grab the screw,
the handwheel, the nut, etc.

FMKWELDING · Jul 8, 2017

If I couldn't find the nut does anyone know the pitch on their feed screw? I have 5/8-10 ordered

Line boring machine help

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