how tough are delrin nuts

[dertsap]

i just purchased two leadscrews that are 3/4'' dia 10 start lead 2"/revolution which is perfect for what i need , the issue i have is the delrin nuts which are two inches long , the way i see it is ive stripped out enough steel bolts and screws over the years which concerns me about using any types of plastics , my motors are 770 oz ,so they deffinitely do not lack torque ,my concern is stripping the screw when or if i hard limit the gantry or at the speeds this thing will be running at upon acceleration it will shred the nut , there will be a small chunk i will need to chop off one so i will be able to make a roll form tap to make spares even possibly roll it thru a piece of aluminum to make a stronger thread (we got a good press at work heh heh !) plus we have a few cnc's with enough torque to tap it as well ,
its not a small machine and its made out of 2x4 steel tubing so it s not light either,the cutting surface will be 3ft x 5ft
should i be concerned ?

[dertsap]

soooo !

anyone ever had problems with wear on their delrin nuts

[Jason Marsha]

Delrin seemd to be the thing to use in nuts as it has an oily feel and excellent wear properties.
As for stripping it in a limit crash, I suppose it is very possible.

Jason

[HayTay]

Delrin is what DumpsterCNC AB Leadnuts are made of. I just converted my X and Y axis to 1/2"-10 single start ACME threaded rod with Dumpster AB leadnuts and the difference is amazing compared to 1/4"-20 all thread with HDPE AB nut assemblies.

I know I'm not running near as fast or as heavy as your machine. But, as you said, you've already stripped a bunch of steel nuts and screws. Sometimes it's counter-intuitive but 'plastic' nuts may work better. Delrin is self-lubricating to an extent and it may give more rather than grinding away and stripping. Running steel leadnuts on steel leadscrews might result in enough galling to lead to their untimely demise. If that's the case the Delrin nuts should alleviate some of the friction and wear.

If I may be so bold, why don't you just 'bite the bullet" and step up to ballscrews?

[dertsap]

ive read posts where guys were quite happy with the delrin thats what brought me to look for opinions , i never liked the idea of using that material so i hope i don t live to regret buying them
suppose i should clarify my point earlier about stripping nuts and screws , that was done with wrenches or what have you ,not on the cnc as a leadscrew
to answer the question on ballscrews ,the price is too high ,
i was hooked up for chain drive ,but when i saw those screws with 2"/rev at 45 bucks apiece with 61" thread ,i was all over them like a fly , they are teflon coated stainless ( some type ? )

[HayTay]

Derstap, my man,

OK, so after reading your last post, are you going to use the Delrin for leadnuts, mounting nuts on the ends of your leadscrews, or both?

about stripping nuts and screws , that was done with wrenches or what have you

I'd say that if you've muscled your steel mounting nuts and screws to failure, mounting nuts made from Delrin won't have a prayer.

You made a major score on the "screws with 2"/rev at 45 bucks apiece with 61" thread"! Got pics? Do you anticipate any problem with the Teflon coating chipping and wearing off of the stainless?

[Geof]

I think you will have to work hard to damage something that diameter Delrin or not. I have used Delrin for large diameter clamping nuts on fixtures and they have survived thousands of cycles. The important thing with Delrin is to have a smooth thread on the steel and use a little bit of lubricant such as White Petrolatum.

[dertsap]

i've worked with the stuff a fair bit over the years and i find it overall not too bad as far as machining goes ,even though its tempermental at times ,but ive never used it in this type of application , concidering the size of thread your probably right about it standing up , they are supposed to be precision teflon coated screws ,so they should be smooth
i will see what i can come up with as far as making a roll tap and make a few spares , i'd love to throw a few onto the machines at work and make them properly but free time on the machines is nearly non existent
now i have to figure out how to utilize the holes ive already drilled into my gantry for the chaindrive , eh maybe limit switches ,
plans are made for changing (again)

ive posted a pic of these , they were shipped yesterday , it will be easy to modify the nuts to antibacklash if needed
it surprises me that noone would have jumped on these when the guy posted them on ebay as a buy it now item

[stratcat50]

Limit switches have saved my equipment several times. They were the first thing I used/tested on my DIY machine. They were important enough to me that I fired up the system without power to the stepper drives and hand-moved all axes to limits to make sure EMC would stop motion.

Just gives you one less thing to worry about.
Good luck,
Emory

[dertsap]

thanks

the nuts seem to be tough enough , my motors definitely stall out before stripping the threads , ive been cutting aluminum and stuff and all works well ,these screws were an incredible find , it tortured me to pull out the cutting disc and chop the y axis screw to size but it had to be done

the limit switches are the next thing in line to complete on the system ,i'm just waiting for the wire to arrive anyday ,i bought a limit switch board from hubbard electronics on ebay for 10 bucks and it works pretty nicely , its sort of idiot proof which at this point of the game is a welcomed add-on , i dont want to blow anything up