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Robot Arm

little ol' e

Jus' a hobby guy
Machining question. The raised part in the inside center seats the tapered roller bearings on each side. The outer bearing races are a press fit. (or heat metal while freezing bearing so it drops in.
I myself, wouldn't use any heat on what your doing.
I would toss the bearing races in the freezer for the day and you should be good to go on day 2 for pressing.
 

curmudgeon

(Steve)
Machining question. The raised part in the inside center seats the tapered roller bearings on each side. The outer bearing races are a press fit.

Could you do almost all of it in one mount:
1) mount a longer than needed piece of stock
2) turn outside surface
3) bore first end
4) face 1'st end
5) back bore opposite end
6) part off
7) re-mount other end, does not need to be aligned with first mounting
8) face 2'nd end,

This is all speculation from the guy who has never used a boring bar and spends too much time watching videos of others making chips instead of practicing myself.
 

jcdammeyer

John
Premium Member
After major issues with my 3D printer I'm back to operational and now have 7 cover parts printed. I do believe the ducks approve.
SevenCoverPartsPrinted.jpg
 

LenVW

Process Machinery Designer
1678537109745.png

John,
Here is a handy style of BASE for your robot.
Sturdy Linear Rails for travel and increased reach.
Can help to extend your application windows.
 

jcdammeyer

John
Premium Member
View attachment 31992

John,
Here is a handy style of BASE for your robot.
Sturdy Linear Rails for travel and increased reach.
Can help to extend your application windows.
Thanks for the link. Yes. The AR4 system has the ability to add the 7th axis which is a track like that. There are a number of youtube videos showing how people have implemented that. I may even have some linear rails left over after my CNC router upgrade.
AlternativeBearing1.jpg
Or use the then freed up linear guides and rod that are currently on the router.
 

PeterT

Ultra Member
Premium Member
And the parts just keep arriving.
Where are you buying the tooth belts/wheels from & what tooth profile / pitch are they?
I had to get some HTD 3m for my next engine, they are a bid more obscure but I did find a supplier I used in the past.
 

jcdammeyer

John
Premium Member
One of the pulleys was sold ss XL profile but has curved rather than flat bottoms in the tooth profile.

Possibly HTD 5mm instead of XL 5.08mm

Might try a different supplier for that pulley.
 

LenVW

Process Machinery Designer
I like your creativity with the angle rail and bearings to reduce friction on the tube.
With less ‘wear’ in a hobbyist shop, I have even used PE slide guides from ice skate guards.
Re-purposing common items, can result in cost-effective components that last ‘hundreds‘ of cycles.
 

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PeterT

Ultra Member
Premium Member
I ordered from these guys. Some things are cheaper elsewhere but they have what they have when you need what you need. Used to be in Germany only, now have a N-Am distributer. I landed on them years ago when I ordered my hard to find (module/tooth) internal ring gear for my radial & other metric goodies. For my recent order via N-Am I selected $10USD shipping option & provide my Fedex account number. Then Fedex spanked my wallet on the CDN side but delivery was quick & painless.

 

jcdammeyer

John
Premium Member
I ordered from these guys. Some things are cheaper elsewhere but they have what they have when you need what you need. Used to be in Germany only, now have a N-Am distributer. I landed on them years ago when I ordered my hard to find (module/tooth) internal ring gear for my radial & other metric goodies. For my recent order via N-Am I selected $10USD shipping option & provide my Fedex account number. Then Fedex spanked my wallet on the CDN side but delivery was quick & painless.

Thanks. I'll look into them.
 

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
I ordered from these guys. Some things are cheaper elsewhere but they have what they have when you need what you need.

Sure wish I knew about these guys back when I made a metric clock. 1000 microdays in a milliday, 10 millidays in a centiday, 10 centidays in a deciday, and 10 decidays in a day , - all with the length of a standard microday defined as 1 millionth of a day. (Note that one second is 1/86,400 of a day.)

Now of course, that still left 365-1/4 days in a year to deal with.....

It was all only intended to ridicule the advantages claimed for the new metric system. 10 being a purely arbitrary unit. 8 would have been infinitely better. If only prehistoric man had left his thumbs out when developing a counting system.

I did think about making an octo clock at the time. It would have been way better than metric or imperial.
 

LenVW

Process Machinery Designer
Maedler has been a respectable name in industrial assemblies for decades.
Their small linear bearings are . . .

Linear Motion Guides DFG 115
Material: Track and carriage from aluminium, hard anodised.
Plain bearings from advanced technical polymer.

Another example of the polymer bearing material and hardened guide.
The key feature is the basic self-lubricating polymer slide bushing.
 

jcdammeyer

John
Premium Member
Here's an update on the incorrect XL pulleys. I only needed one of the 15T XL series. But they came in pairs from AliExpress reseller. For $5 or so including shipping. However they had the curved tooth profile for the metric pulleys. Even though the web site and the order said XL series. Pitch is 5.08mm rather than 5mm.

Now you'd think that probably wouldn't be a problem but it turns out there's a fair amount of slop between the XL belt and the metric pulley. Well today two XL 15T pulleys from a different supplier arrived. I held my breath hoping that it wasn't another identical screw-up.

Nope. They are beautiful. Also only about $5 for the two.

XL_Pulley.jpg

Also in the same package (AliExpress have been combining packages to save on local shipping) I received the 3mm OD x 1mm ID silicon tubing and both fast attach couplers and ones with nibbles to slide the tubing onto. The tubing is too software for the fast attach. However the other ones are great. Tubing slides onto the nipple and then the knurled nut threads on and compresses against the tubing to hold it tight. As it is it's hard to remove again anyway.

The other end of the tubing will go to a little adaptor manifold I have to make to upsize to the standard 1/4" tubing for the valve. That's 3mm threaded to 1/4" pipe thread.

Gripper-1.jpg
Unfortunately a work-work project surfaced and I'll be busy for quite some time before I can continue with this project. :(

Edit: What I meant is the XL pulleys are 5.08 mm while the metric ones are 5mm. And the photo is showing one of each and the XL belt just to show the differences.
 
Last edited:

DavidR8

Scrap maker
Administrator
Moderator
Premium Member
Here's an update on the incorrect XL pulleys. I only needed on 15T XL series. But they came in pairs from AliExpress reseller. For $5 or so including shipping. However they had the curved tooth profile for the metric pulleys. Even though the web site and the order said XL series. Pitch is 5.08mm rather than 5mm.

Now you'd think that probably wouldn't be a problem but it turns out there's a fair amount of slop between the XL belt and the metric pulley. Well today two XL 15T pulleys from a different supplier arrived. I held my breath hoping that it wasn't another identical screw-up.

Nope. They are beautiful. Also only about $5 for the two.

View attachment 32942

Also in the same package (AliExpress have been combining packages to save on local shipping) I received the 3mm OD x 1mm ID silicon tubing and both fast attach couplers and ones with nibbles to slide the tubing onto. The tubing is too software for the fast attach. However the other ones are great. Tubing slides onto the nipple and then the knurled nut threads on and compresses against the tubing to hold it tight. As it is it's hard to remove again anyway.

The other end of the tubing will go to a little adaptor manifold I have to make to upsize to the standard 1/4" tubing for the valve. That's 3mm threaded to 1/4" pipe thread.

View attachment 32943
Unfortunately a work-work project surfaced and I'll be busy for quite some time before I can continue with this project. :(
Blasted work-work always getting in the way of playtime!
 

jcdammeyer

John
Premium Member
I have some free time which means I'm too lazy to go out and do yard work. So I thought I'd make up a list of the Spaenaur part numbers for all the screws in the AR3 Robot Arm kit.
There are number of flat head and pan head machine screws of the metric variety. For example M3x5 Flat Head. These are available in both Socket head and Philips head.
Another example is M4x20 Pan Head which is available in Slotted or Philips.
The question is: Socket or Philips; Slotted or Philips.

What are the advantages of one over the other? Assuming the price is similar.
 

jcdammeyer

John
Premium Member
I've been making up a list at AliExpress since I need 32 different screw types. I think I will finish the spreadsheet of all the screws and get Spaenaur to quote but for this cheap (well not really cheap) robot arm I'm not sure I need an extra 87 screws if I have to buy a box of 100.

Even McMaster Carr can supply these of which I need 13 according to the parts list.
1684980253822.png

Where AliExpress wants 1/2 of that but of course I'll have to probably wait a month where McMaster Carr will ship on Friday.
1684980370123.png

I wonder if the quality is any different. Shipping is about $25 from McMaster Carr.
 
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