[R_garza]

This is what I have so far. I've been working on the metal part before I start on the base. I'm not planning on making the whole base, but probably just a simple sturdy frame. I messed up on the drilling, especially on the 1/4 holes since I drilled them with a 1/4 bit before I got the tap, so now I can't thread them. I was thinking of using jbweld to fill up the holes and drill them again, but I was reading it might not be that good. I'll probably just buy some helicoils from harbor freight to repair them. I still need to do some filing and finish some of the other parts. I did come up short on material for parts 15 and 27.

And these are the parts I've collected so far. I originally ordered the 3 axis sidestep from Probotix, but they decided to upgrade me to the probosteppers for free plus upgraded my shipping also. Don't know why, never asked and keep forgetting to send a thank you for that.
I was thinking of trying their pbx-usb so I can use my mac, wondered if any one had tried it yet?

I still need to get a few other parts like the rails and gantry, but I'm gonna check to see if I can find those locally.

[kemper45]

R Garza,

Thanks for sharing your build with the group. Bummer on the mistake with the 1/4" holes. Just a thought - could you tap them with the thread size that corresponds to the 1/4" hole and then buy some more all thread rods to match that and cut your studs again? Might be easier than the helicoils - I wouldn't know as I have not used them before.

Sorry can't help on the Mac question, hopefully someone else can chime in.

Dave

[Michael In Cali]

Tap drill for a 5/16-18 thread is a leffer "F" drill at .2570". I would redrill with an "F" and go to 5/16 all-thread. Should be a quick fix.

Helicoils are about $0.50 each or a bit more. Changeing to 5/16 all-thread will be cheaper. If I recall correctly, HF only has the helicoils, not the required tap and insert tool. For those an auto parts store would be a beter place to go. And, those tools are expensive as well. All around, cheaper to change to 5/16 threads.

JB weld will not work.

Nice to see another build thread. I'll get mine started when I can actually make a commitment and quit optimizing the deaign.

[bjesson]

Tap drill for a 5/16-18 thread is a leffer "F" drill at .2570". I would redrill with an "F" and go to 5/16 all-thread. Should be a quick fix.

Helicoils are about $0.50 each or a bit more. Changeing to 5/16 all-thread will be cheaper. If I recall correctly, HF only has the helicoils, not the required tap and insert tool. For those an auto parts store would be a beter place to go. And, those tools are expensive as well. All around, cheaper to change to 5/16 threads.

JB weld will not work.

Nice to see another build thread. I'll get mine started when I can actually make a commitment and quit optimizing the deaign.

Yeah upping everything to 5/16-18 allthread would probably be the better option. In some of those locations you can also use 1/4-20 caphead screws to save you from having to perform a bunch of extra steps. One thing to consider is if you up everything to 5/16 you will have to redrill all the mating parts to accept the bigger diameter allthread. This will be a problem mostly in the Z-plate and nut plate locations where the mounting bolts/nuts clearance is already extremely tight with 1/4-20. one thing to consider in this location is just flipping the Z plate and redrilling/tapping the holes to 1/4-20. In the locations you do ultimatley use 5/16 allthread in you probably dont have to redrill with an F drill, 5/16 tap is bulky and your only talking about .007" difference which is tiny and unless you used a really nice expensive drill bit then the tolerance of a standard bit is negligible, be sure to use tapping fluid though. Good Luck!

And yes, Mike has it right, auto parts stores have the full setup for helicoils, you stripped a few threads in your day too I see Mike

billj

[bjesson]

I am so jealous of the yellow steppers!

Which type of timing belt did you use? I used kevlar reinforced and was going to try out steel reinforced but the kevlar has performed perfectly.

billj

[Michael In Cali]

And yes, Mike has it right, auto parts stores have the full setup for helicoils, you stripped a few threads in your day too I see Mike
billj

Always fixing someone else's mistake I never make mistakes. Really, honest, I promise.

At work, it is routine to put an insert into aluminum threads. Bare aluminum threads are a no-no for multiple insertion applications and applications with significant load. Usually we use a key-insert as helicoils are prone to coming out. But, key-inserts are larger and more expensive and unnecessary for this build.

To the OP, I would work each hole as you build things up. Some places may work better with just using a nut and washer instead of going up to 5/16. Let each location dictate the required fix. If I remember the design correctly, the Z-stepper mount may be problematic as there is no room for two 5/16 nuts. Two 1/4" nuts are tight there. You might end up with two 5/16 cap screws with the heads inserts in opposite sides forthat location.

[bjesson]

This is what I have so far. I've been working on the metal part before I start on the base. I'm not planning on making the whole base, but probably just a simple sturdy frame. I messed up on the drilling, especially on the 1/4 holes since I drilled them with a 1/4 bit before I got the tap, so now I can't thread them. I was thinking of using jbweld to fill up the holes and drill them again, but I was reading it might not be that good. I'll probably just buy some helicoils from harbor freight to repair them. I still need to do some filing and finish some of the other parts. I did come up short on material for parts 15 and 27.

And these are the parts I've collected so far. I originally ordered the 3 axis sidestep from Probotix, but they decided to upgrade me to the probosteppers for free plus upgraded my shipping also. Don't know why, never asked and keep forgetting to send a thank you for that.
I was thinking of trying their pbx-usb so I can use my mac, wondered if any one had tried it yet?

I still need to get a few other parts like the rails and gantry, but I'm gonna check to see if I can find those locally.

Not sure what you mean by building a simple sturdy base but of all areas not to follow the plans this isnt the one. Your better off building the base as designed for multiple reasons but to each his own. Throw some pics up when you have completed, always interesting to see what works for others.

Billj

[R_garza]

Thanks for all the help guys.

bjesson, the belt is the kevlar from mcmaster. For the base I was thinking about the open frame from the David Steele plans, something along those lines, but still keeping the same dimensions.

kemper45, I can't thread the holes at 1/4 since they're already to big. I already bought the helicoils, hopefully they'll work ok.

Michael, I was thinking about using a nut to hold the other end of the rod, but like you said it will probably be a problem in some places. The helicoils came out to $4 for a 10 pack, I needed 3 packs. I already had a tap lying around for the 5/16 they require so I'm going to try those out.

[Michael In Cali]

Thanks for all the help guys.

bjesson, the belt is the kevlar from mcmaster. For the base I was thinking about the open frame from the David Steele plans, something along those lines, but still keeping the same dimensions.

kemper45, I can't thread the holes at 1/4 since they're already to big. I already bought the helicoils, hopefully they'll work ok.

Michael, I was thinking about using a nut to hold the other end of the rod, but like you said it will probably be a problem in some places. The helicoils came out to $4 for a 10 pack, I needed 3 packs. I already had a tap lying around for the 5/16 they require so I'm going to try those out.

Double check that tap. Helicoils need a special tap. Since its just a diamond shaped coil of wire, the new threads you cut must match the intended 1/4-20 thread. 5/16 is normally either 18 or 24 pitch. Thus you use a special 5/16-20 tap. Heck, I'm not sure its even 5/16, I just get the tap "for 1/4-20 helicoils" and never checked.

Now, if your using key-inserts, thats different as they can (and usually do) have different internal and external threads and use standard threadforms. But those are bigger. Much bigger and likely won't fit for your repair.

[bjesson]

Thanks for all the help guys.

bjesson, the belt is the kevlar from mcmaster. For the base I was thinking about the open frame from the David Steele plans, something along those lines, but still keeping the same dimensions.

kemper45, I can't thread the holes at 1/4 since they're already to big. I already bought the helicoils, hopefully they'll work ok.

Michael, I was thinking about using a nut to hold the other end of the rod, but like you said it will probably be a problem in some places. The helicoils came out to $4 for a 10 pack, I needed 3 packs. I already had a tap lying around for the 5/16 they require so I'm going to try those out.

Make sure you threadlock the helicoils and let them sit overnight before threadlocking the studs. Another way I found worked well was using Gorilla CA glue so no need to wait 24 hours for it to cure. This stuff cures in a matter of minutes and is as strong if not stronger then high strength threadlock.

billj

[R_garza]

Here's one of the parts I was trying out the helicoils on, they seem to be working ok, they just get stuck once I put them in so I have to put thread locker first. I had to use a 9/32 bit for the drill size since I couldn't find a 17/64 for tapping 5/16, but it still seems like a good hold. Now I just have 20 more to fix.

[Michael In Cali]

Looks good. You obviously had the correct tap, so you've been down this road before.

What we do in a prduction environment is install them with wet primer. The primer does two things. It locks the helicoils in place and it also provides a corrosion barrier. Again, not appropriate here, but thats whatwe do. You get a galvanic couple between the aluminum and steel and it promotes corrosion, so you use the primer as a barrier. Not the easiest things to replace though.

You can also use the green thread locker. Its a wicking thread locker and can be used post-installation. Only used it a few times myself but its preferred on very small fasteners like #4.

[R_garza]

Well I can't believe all the trouble I'm having with these parts. I installed all the helicoils with threadlock, but now I can't seem to put the studs in. It seems like the helicoils opened up more when I stalled them although there didn't seem to be a problem when I tested them out the first time. I'm not sure whether to order the aluminum and start again, which would probably be better, but I would stay with all these extra parts. Unless I find a way to remove the helicoils and try something else. Just another learning experience I guess.

[Michael In Cali]

Well I can't believe all the trouble I'm having with these parts. I installed all the helicoils with threadlock, but now I can't seem to put the studs in. It seems like the helicoils opened up more when I stalled them although there didn't seem to be a problem when I tested them out the first time. I'm not sure whether to order the aluminum and start again, which would probably be better, but I would stay with all these extra parts. Unless I find a way to remove the helicoils and try something else. Just another learning experience I guess.

Back to first principles...

Tell me how you know you used the right tap? Is the tap a 5/16-20? Is it marked as a helicoil tap?

[R_garza]

The package of helicoils just said to use 5/16, it didn't specify 20 or anything else. I think the tap I used was an 18, but like I said when I first made the the tap the helicoil would go in fine with the stud, but no I don't think it was the right tap. It looks like I need to scrunch down the helicoils for the studs to go in without any force or remove them and fasten the studs another way

[Michael In Cali]

Re-read my post #9. You will never get a 20 pitch screw in a 18 pitch hole.

How to get well. Lets see if we can get the helicoils out without too much damage. Heat the aluminum up and see if you can break the bond and get the helicoils out with a dental pick or something. If you can, you can use the existing 5/16-18 threads and get 5/16 all-thread for the studs. I'd hate to see all your hard work go to waste.

If it were me, I'd take a couple of pieces of aluminum bar and bake it in gas grill for a while. Its runs at about 400-500 degrees. Your oven would work too. I'm not too much keen on torch work, but a propane torch will work too. Its just easier with an oven.

[bjesson]

if it all worked originally then maybe you just got some threadlock on the inside threads, you can always clear the threads with a 1/4-20 tap and see where that gets you. I you do want to remove the helicoil then as Mike siad, oven works great. 400 degress for 30 minutes should do the trick, be sure to use oven mits though

Just seems odd it all worked before threadlock was applied, next time if you have not completed all the helicoil fixes try working the oppoiste way, threadlock the studs into the helicoils then the helicoils to the aluminum piece.

Good luck!
billj

[Michael In Cali]

if it all worked originally then maybe you just got some threadlock on the inside threads, you can always clear the threads with a 1/4-20 tap and see where that gets you. I you do want to remove the helicoil then as Mike siad, oven works great. 400 degress for 30 minutes should do the trick, be sure to use oven mits though

Just seems odd it all worked before threadlock was applied, next time if you have not completed all the helicoil fixes try working the oppoiste way, threadlock the studs into the helicoils then the helicoils to the aluminum piece.

Good luck!
billj

Bill, he really needs to step back and check his work first. If he chases the threads with a tap he may make removal a bigger problem.

He really needs to confirm the pitch of the tap and make sure he has or hasn't got 20 pitch threads.

Also, I would not lock the helicoil to the stud first. Thats not the way helicoils are supposed to be installed.

First principles first. Something is buggered up and we don't know what yet, so fixing it is secondary to figuring out the problem right now.

[bjesson]

Bill, he really needs to step back and check his work first. If he chases the threads with a tap he may make removal a bigger problem.

He really needs to confirm the pitch of the tap and make sure he has or hasn't got 20 pitch threads.

Also, I would not lock the helicoil to the stud first. Thats not the way helicoils are supposed to be installed.

First principles first. Something is buggered up and we don't know what yet, so fixing it is secondary to figuring out the problem right now.

Mike, I agree for the most part, but we are also trying to resolve a problem based on his statements. He originally stated it all worked until he threadlocked it. From his phrase to me it sounded like he installed helicoil and stud and was comfortable enough with the fit to proceed to use threadlock at which point nothing worked anymore. The only thing that changed from the original working equation was threadlock. Finger threading a tap into the helicoil to see if there is indeed any threadlock in the way is quick, doesn't require an oven, and will not ruin the threads as helicoils are a tough steel. And I agree, helicoils are not supposed to be installed on a stud first then into the tapped hole they are to finally sit in but if we all went but the instructions on the box we would never have made it to the moon So, easiest nd fastest way to check tap thread count is hold the threads from the helicoil against the theads of the tap and see if they intermesh or align perfectly, if they dont, the tap is obviously incorrect. I just dont know how it would be possible to thread a 5/16-18 helicoil into a 5/16-20 threaded hole without it being obviously not a good fit. You can fairly easily thread a 5/16-20 Helicoil into a 5/16-18 thread because it will expand to the courser thread pitch but in turn change the internal thread pitch. Or better yet, just go to home depot and get a 5/16-18 tap for $6, remove all helicoils with the oven, and start from scratch.

Keep us posted on what fixes your issue!

billj

[Michael In Cali]

Mike, I agree for the most part, but we are also trying to resolve a problem based on his statements. He originally stated it all worked until he threadlocked it. From his phrase to me it sounded like he installed helicoil and stud and was comfortable enough with the fit to proceed to use threadlock at which point nothing worked anymore. The only thing that changed from the original working equation was threadlock. Finger threading a tap into the helicoil to see if there is indeed any threadlock in the way is quick, doesn't require an oven, and will not ruin the threads as helicoils are a tough steel. And I agree, helicoils are not supposed to be installed on a stud first then into the tapped hole they are to finally sit in but if we all went but the instructions on the box we would never have made it to the moon So, easiest nd fastest way to check tap thread count is hold the threads from the helicoil against the theads of the tap and see if they intermesh or align perfectly, if they dont, the tap is obviously incorrect. I just dont know how it would be possible to thread a 5/16-18 helicoil into a 5/16-20 threaded hole without it being obviously not a good fit. You can fairly easily thread a 5/16-20 Helicoil into a 5/16-18 thread because it will expand to the courser thread pitch but in turn change the internal thread pitch. Or better yet, just go to home depot and get a 5/16-18 tap for $6, remove all helicoils with the oven, and start from scratch.

Keep us posted on what fixes your issue!

billj

And I agree with you for the most part...

Its impossible to purchase a 1/4-18 helicoil, so we know the helicoil is not the problem. Helicoils are purchased to the inside thread, so its a 1/4-20 helicoil, not a 5/16 diameter helicoil. Since he purchased 1/4" helicoils his only options are 20 pitch or 28 pitch. Since he purchased at harbor freight, the only thing they sell is a 1/4-20. (and apparently no drills or taps or insertion tools last I checked).

To see if he has the correct tap he can do two things. Firstly, just read the printing on the tap shaft. It should state its application, including pitch.

Instead of measuring the helicoil, he should measure the 1/4-20 bolt as compared to the tap. He can, as you said, just lay the two parallel and mesh the threads and see if they mesh for the entire length. the must mesh for the entire length.

Now that I've had my coffee this morning, I'm thinking that there is a high likelyhood that cured threadlock is impeding the stud insertion and seizing the stud as its inserted and chasing the threads with a 1/4-20 tap is a good idea. (so I'm agreeingwith you here )The helicoil is actually stainless steel and subject to galling so its not optimum, but its worth it. Also, actually, you are not supposed to us a standard cutting tap for chasing threads, there are special thread repair taps for that, but everyone does it and in this application it not critical anyway.

So, to recap things to do.

1) verify the tap thread pitch and describe to us any marking on the tap.
2) chase the threads on some selected part using a 1/4-20 tap and lubrication. Verify that a stud fits.
3) report finding back.
4) attempt to remove a helicoil with heat and a dental pick. Then use a 5/16-18 stud if thats how the hole got tapped.