Saturn 2 4x4 - Nema 23

[PLJack]

I wouldn't bother, as putting T nuts in is a lot of work.

What I would do, is surface the first layer. Then glue the second layer down to the first. I'd pre-drill the top layer, and use wood screws every 6 inches or so. Then remove the screws when the glue dries.

That sounds like a proper solution. Sounds pretty stout. But I've decided to try something I have not seen before. I'm still going take a risk with the T-Nuts. Clamping was a real b**ch with my tabletop CNC. Should have pictures in a few days.

Thanks.
Jack.

[PLJack]

That is definitely looking good, Jack.

Thanks David. Should be really close to final tweaking by end of next week.

I started out with a triangle and switched to large squares and rectangles so I could measure the diagonals both ways and then compare. It took some tweaking but I finally got it down to as close to dead perfect as my eyes and measuring capabilities allow over a 52" diagonal.
David

Seems the way to go.

Thanks.
Jack.

[PLJack]

Just an outside shot, but could the creaking your hearing be a cable chain? I was hearing odd noises, and that's what it turned out to be.
Gary

Turns out not to be the case but your suggestion got me thinking. I might just be hearing the wood platform creaking and because it's tight to the frame the noise is transferring to the steel like a musical instrument. I once leaned against the machine while I was looking at something and heard the same "clang" as the friction of the wood against the steel gave way.
Then the other day while moving the Y axis towards me I heard the creaking and could have sworn I saw the B sled jump forward like it was binding.

So, jury is still out on that one.

Thanks. Gary.

Jack.

[difalkner]

The screws I used are nylon and were $11 for 100 - didn't seem too expensive to me. These particular ones show as not available now on Amazon but they're bound to have others.

David

[PLJack]

The screws I used are nylon and were $11 for 100 - didn't seem too expensive to me. These particular ones show as not available now on Amazon but they're bound to have others.

David

Those are perfect David. Nothing wrong with that price. Thanks. The ones I saw on Amazon were double digits for a handful.
They must be on to me. I swear every time I click buy the next screen says. "Thanks for your order. Listed below are some things you spent 40 minutes looking for but couldn't find."

Jack.

[PLJack]

FYI:
Heard that pop again tonight. Always from the right side. Caught it on video but I don't see anything "pop".

Video :

Few notes:
Seems to always happen coming from back to front.
Seems to always be about 2/3's down the rail from the back.
That wobble on the motor shaft belt gear is just the thin metal at the end that keeps the belt on. I slightly bent it a month ago. Just cosmetic.

Thanks.
Jack.

[GME]

Jack,

Beats me. I don't see anything, but the sound is clearly audible. It's a very different sound than I heard from my cable chain.

Have you tried putting your hand on the right side of the gantry while it's moving to see if you can feel something? If nothing there, you might start putting you hand on various parts of the machine to see if you can feel something.

Gary

[difalkner]

Interesting... for months I've noticed ours has a very slight pop on the right side but it is so slight, maybe 10% as loud as yours, that I have just ignored it. I know the machine is well lubricated and when I had the pinions disengaged to change those out I moved the gantry by hand over the entire range to see if I could feel anything. Nothing felt out of order and I only hear the slight noise when the machine is cold and I'm running the gantry from back to front for homing. After that I never hear it again - weird.

David

[DDgitfiddle]

Interesting... for months I've noticed ours has a very slight pop on the right side but it is so slight, maybe 10% as loud as yours, that I have just ignored it. I know the machine is well lubricated and when I had the pinions disengaged to change those out I moved the gantry by hand over the entire range to see if I could feel anything. Nothing felt out of order and I only hear the slight noise when the machine is cold and I'm running the gantry from back to front for homing. After that I never hear it again - weird.

David

Take a close look at the rack on that side. If there is debris, a small burr in the rack, or even a little weld splatter near where the clunk happens it could be causing the noise.

The anti-backlash adjustment (spring) on these drives is a little bit of a hack, strictly speaking. Backlash is necessary in gears to keep the tips of the teeth from contacting the faces of the mating teeth. There is always a little error in machining the teeth on the pinions and the racks. The more error there is, the more backlash you need to avoid interference. This rack and pinion system is not the highest grade and was not originally designed to have the pinion pushed all the way into the rack. It would cost alot more to get higher grade (more accurate) gearing. That said, the anti-backlash adjustment generally works pretty well for this application. You may just be seeing a spot where there is a little more interference than typical. A small burr, even 0.001"-0.002" is significant in gears this size.

-Robert

[PLJack]

Jack,

Beats me. I don't see anything, but the sound is clearly audible. It's a very different sound than I heard from my cable chain.

Have you tried putting your hand on the right side of the gantry while it's moving to see if you can feel something? If nothing there, you might start putting you hand on various parts of the machine to see if you can feel something.

Gary

I'm doing some work on the machine tonight. If the sound shows up again I will do that.

[PLJack]

Interesting... for months I've noticed ours has a very slight pop on the right side but it is so slight, maybe 10% as loud as yours, that I have just ignored it. I know the machine is well lubricated and when I had the pinions disengaged to change those out I moved the gantry by hand over the entire range to see if I could feel anything. Nothing felt out of order and I only hear the slight noise when the machine is cold and I'm running the gantry from back to front for homing. After that I never hear it again - weird.

David

That is interesting.. Same description and order of events.
Any idea roughly where your tension screw is in reference to the bottom of the nut? Mine is about three threads past the bottom.


Thanks.
Jack

[wmgeorge]

Take a close look at the rack on that side. If there is debris, a small burr in the rack, or even a little weld splatter near where the clunk happens it could be causing the noise.

The anti-backlash adjustment (spring) on these drives is a little bit of a hack, strictly speaking. Backlash is necessary in gears to keep the tips of the teeth from contacting the faces of the mating teeth. There is always a little error in machining the teeth on the pinions and the racks. The more error there is, the more backlash you need to avoid interference. This rack and pinion system is not the highest grade and was not originally designed to have the pinion pushed all the way into the rack. It would cost alot more to get higher grade (more accurate) gearing. That said, the anti-backlash adjustment generally works pretty well for this application. You may just be seeing a spot where there is a little more interference than typical. A small burr, even 0.001"-0.002" is significant in gears this size.

-Robert

All gears have backlash, you can reduce it by shimming or other adjustment. Too tight and temperature changes or other changes can cause issues. Why is a spring loaded engagement a "hack" how else would you hold the the gears in place? You need to look at the work David does with his machine making guitars, the detail in the inlay and tell me the gearing of this rack and piñon is lacking.

[ger21]

Why is a spring loaded engagement a "hack" how else would you hold the the gears in place?

Because the pinion is supposed to be run at a fixed distance from the rack, not pushed into it as tight as possible.

Spring loading the pinion is an easy way to remove the backlash, and get a usable system at a low price. The downside is that the pinions wear a lot faster.

Higher end rack and pinion systems use helical racks and double pinions to remove backlash.

[difalkner]

That is interesting.. Same description and order of events.
Any idea roughly where your tension screw is in reference to the bottom of the nut? Mine is about three threads past the bottom.

Thanks.
Jack

If we're talking about the same tension screw yours is way tighter than mine. Do we have the same spindles and belt sizes?

David

[PLJack]

If we're talking about the same tension screw yours is way tighter than mine. Do we have the same spindles and belt sizes?

David

They are tighter. For no reason really. Thought I read somewhere there should be a few threads below the nut.
Not sure if they are the same size as yours. Mine is a Saturn V2.





I wonder if I should experiment with backing them off a bit.

Thanks David.
Jack.

[wmgeorge]

They are tighter. For no reason really. Thought I read somewhere there should be a few threads below the nut.
Not sure if they are the same size as yours. Mine is a Saturn V2.





I wonder if I should experiment with backing them off a bit.

Thanks David.
Jack.

Yes mine were too tight, and causing issues.

[wmgeorge]

Because the pinion is supposed to be run at a fixed distance from the rack, not pushed into it as tight as possible.

Spring loading the pinion is an easy way to remove the backlash, and get a usable system at a low price. The downside is that the pinions wear a lot faster.

Higher end rack and pinion systems use helical racks and double pinions to remove backlash.

Gerry what brand of router uses helical racks and double pinions? BTW mine are not that tight, and neither is Davids.

[PLJack]

BTW mine are not that tight, and neither is Davids.

Thanks guys. Very helpful.
I'm about to cut the top layer of MDF tonight. After all the work I did prepping I'm hesitant to make any changes. I'm going to try the run as is.
Definitely will back off the tension screws after that.

Jack.

[DDgitfiddle]

Because the pinion is supposed to be run at a fixed distance from the rack, not pushed into it as tight as possible.

Spring loading the pinion is an easy way to remove the backlash, and get a usable system at a low price. The downside is that the pinions wear a lot faster.

Higher end rack and pinion systems use helical racks and double pinions to remove backlash.

Exactly! I couldn't have said it better myself. I'm not disparaging the FineLine (and similar CNCRP) rack and pinion system. It is designed to a price point and a purpose and does a nice job. I am thrilled with my Saturn 4x2. I considered designing and building my machine myself but realized that I couldn't really match the Saturn for the price. The only drive systems I have seen that look a little nicer in this price range are the tapered rack and pinion systems that KHK America sells:

https://www.khkgears.us/catalog/?cid...strcpf-strcpfd

Or an interesting anti-backlash system from DamenCNC.

https://www.damencnc.com/products/mechanical-components/rack-pinion/q10-straight-rack-pinion/r-p-drive-antibacklash-diy-includes-gears15t/_404_w_363_554_GB_1

I'm not sure how well either would retrofit on a Saturn, though, without alot of work.

-Robert

[wmgeorge]

Exactly! I couldn't have said it better myself. I'm not disparaging the FineLine (and similar CNCRP) rack and pinion system. It is designed to a price point and a purpose and does a nice job. I am thrilled with my Saturn 4x2. I considered designing and building my machine myself but realized that I couldn't really match the Saturn for the price. The only drive systems I have seen that look a little nicer in this price range are the tapered rack and pinion systems that KHK America sells:

https://www.khkgears.us/catalog/?cid...strcpf-strcpfd

Or an interesting anti-backlash system from DamenCNC.

https://www.damencnc.com/products/mechanical-components/rack-pinion/q10-straight-rack-pinion/r-p-drive-antibacklash-diy-includes-gears15t/_404_w_363_554_GB_1

I'm not sure how well either would retrofit on a Saturn, though, without alot of work.

-Robert

Well the carriage alone is over $400 each side in USD, plus upgrading the racks, so we are talking $1000 - $1200 more? Did you see the work David does fitting inlays on his guitars? Fantastic. Same rack and pinion we have on ours.

My spring tension is from the top of the black bracket to the top of the washer over the spring is 1 inch.