Need to get the right Lovejoy coupling. Can anyone help?

[alexccmeister]

Hi all,

I am going to convert my XY axes to cnc on my X2 mill and I need to use the stock leadscrews on both axes. I also have a couple of Nema23 stepper motor with 1/4" (6.3mm) shaft. The leadscrew end has a shaft diameter of 0.3937" (10mm).

I have checked out lovejoy coupling at enco and the coupling normally comes in a set having the same bore diameter (am I right?) So if what I need to couple are of different diameter, is it possible to use two different hub bore diameter? Or I have to resort to either turn down the lead screw end to 0.25" in order to use the 0.25" bore diameter coupling or add something to the shaft of the stepper motor so I can use a 0.3937" bore diameter coupling?

Thanks in advance.

[digits]

Originally Posted by alexccmeister Hi all, I am going to convert my XY axes to cnc on my X2 mill and I need to use the stock leadscrews on both axes. I also have a couple of Nema23 stepper motor with 1/4" (6.3mm) shaft. The leadscrew end has a shaft diameter of 0.3937" (10mm). I have checked out lovejoy coupling at enco and the coupling normally comes in a set having the same bore diameter (am I right?) So if what I need to couple are of different diameter, is it possible to use two different hub bore diameter? Or I have to resort to either turn down the lead screw end to 0.25" in order to use the 0.25" bore diameter coupling or add something to the shaft of the stepper motor so I can use a 0.3937" bore diameter coupling? Thanks in advance. Attachment 38532

I think that as long as the coupler bodies are the same diameter, you can just buy two different bore sizes and then use one half from each set - I have certainly bought couplers with different bores on each end before.

My new machine has couplers that you have to but in 3 parts anyway - two jaws and a synthetic rubber 'spider' - this lets you mix and match. Unfortunately I ordered 12mm bores for everything, and my ballscrews are all cut to 10mm diameter - D'oh! Fortunately I can simply slip a piece of 12mm dia aluminium tube over the end of the screws, and that clamps perfectly tightly in the 12mm coupler, but I may add loctite before final assembly. This might work for your steppers, but buying the correct pair of bores is obviously eaier.

For my motors though, I actually have to drill out my couplers from 12mm to 1/2" - 12.7mm. I can do this fairly accurately by clamping them in a vice, and then positioning the coupler under the spindle such that a 12mm drill bit will go straight through the existing bore without touching the sides of the hole - with the spindle off, obviously! Then I simply raise the head, swap to a 1/2" drill and slowly drill out the hole to size.

Hope that helps.

[alexccmeister]

Hi Digits,

Thanks. That really helped. Where did you get your coupling?

The coupling at Enco seems to be all in plastic. Aren't they suppose to be steel?

Thanks.

[digits]

Originally Posted by alexccmeister Hi Digits, Thanks. That really helped. Where did you get your coupling? The coupling at Enco seems to be all in plastic. Aren't they suppose to be steel? Thanks.

You are welcome

I got my couplers from a UK supplier: rswww.com - they have a load of different couplers, none of them particularly cheap, but they do seem to be of good quality. I went for aluminium couplers with a synthetic 'spider' in the end, though they also do cast-iron 'Lovejoy' branded couplers.

Cheers.

[zwdeal]

Originally Posted by alexccmeister Hi all, I am going to convert my XY axes to cnc on my X2 mill and I need to use the stock leadscrews on both axes. I also have a couple of Nema23 stepper motor with 1/4" (6.3mm) shaft. The leadscrew end has a shaft diameter of 0.3937" (10mm). I have checked out lovejoy coupling at enco and the coupling normally comes in a set having the same bore diameter (am I right?) So if what I need to couple are of different diameter, is it possible to use two different hub bore diameter? Or I have to resort to either turn down the lead screw end to 0.25" in order to use the 0.25" bore diameter coupling or add something to the shaft of the stepper motor so I can use a 0.3937" bore diameter coupling? Thanks in advance. Attachment 38532

At McMaster:

6408K111 Flexible Spider Shaft Coupling Hub 1/4" Bore, 1-5/64" OD
6413K112 Metric Spider Coupling Hub 10 mm Bore, 1-5/64" OD
6408K91 Hytrel Spider for 1-5/64" Outside Diameter Flexible Spider Shaft Coupling Hub

These should work for you, check them out. I picked Hytrel spider for 50 lb-in capability here, you can pick Buna-N type which is rated at 26 lb-in torque.

[massajamesb]

Here, try this out.
http://surpluscenter.com/sort.asp?UI...s&keyword=PSF3

I used 1/4" bore halves on my motors, and 1/2" halves on the drive components. They are the same part, just different bore. Lines up fine.

[casy_ch]

For people on the other side of the pond, you can get them at www.cnc-plus.de . As somebody said, you have to buy 3 parts and so it is so possible to have two different hole diameters.

Regarding the cross coupling it must be of synthetic material to have a breakdown part if something happens. Cheaper than replacing the step motor!

Jean-Claude, Switzerland

[cueshark]

on ebay search for# 330120602098 that is a 3/8 but he sell some in 3 parts all the same outside different bores. i have bought several items & have always been very satisfied. greg

[edo]

I don't know what the Lovejoy couplers from Enco are made out of, but they aren't plastic. Their Lovejoy website talks about powder metal presses. I can tell you they're ferrous.

The couplers are not sold as a set - you have to order the parts separately. I use them on my CNC router to mate the 1/4" stepper motor shafts to 1/2" Acme rod. They work great. Now that I have my lathe, I'll turn the Acme rods to 3/8" with a flat for the set screw. I haven't seen them in metric, so you'll either have to bore out the 3/8" (.375) to accept the .3937" lead screw or turn down the screw to 3/8". Personally, I'd take digit's advice on boring them - that's a great idea using a drill to center it and changing bits.

Part numbers are 990-4044 for the 1/4" ($1.97), 990-4045 for the 3/8" ($1.97), and 990-4042 for the Buna Spyder ($1.30). (Total $5.24 for the entire coupling as opposed to the eBay seller's $4.99 for just one end.)

The Buna is rated at 26.3 in/lbs. They have a urethane spyder (Part # 619-3475) that is more expensive ($5.49) but is rated 39.4 in/lbs.

I just bought the HF MiniMill last weekend and ordered end mills and collets from Enco last night. Orders more than $50 get free shipping with code WBJR7.

Let us know how the CNC Conversion goes - it's next on my list of things to do too.
Ed

[alexccmeister]

At McMaster: 6408K111 Flexible Spider Shaft Coupling Hub 1/4" Bore, 1-5/64" OD 6413K112 Metric Spider Coupling Hub 10 mm Bore, 1-5/64" OD 6408K91 Hytrel Spider for 1-5/64" Outside Diameter Flexible Spider Shaft Coupling Hub These should work for you, check them out. I picked Hytrel spider for 50 lb-in capability here, you can pick Buna-N type which is rated at 26 lb-in torque.

ZWdeal, Thanks for the part nos. Will definitely check them out.

Here, try this out. http://surpluscenter.com/sort.asp?UI...s&keyword=PSF3 I used 1/4" bore halves on my motors, and 1/2" halves on the drive components. They are the same part, just different bore. Lines up fine.

Massa, great link. Lots of choices. If there are any more links for this thing, that will be great. I have been searching on the net for lovejoy coupling and all I get is a few website like thomasnet, enco and ebay.

For people on the other side of the pond, you can get them at www.cnc-plus.de . As somebody said, you have to buy 3 parts and so it is so possible to have two different hole diameters. Regarding the cross coupling it must be of synthetic material to have a breakdown part if something happens. Cheaper than replacing the step motor! Jean-Claude, Switzerland Reply With Quote

Jean-Claude, Thanks for the link. I think Euro may be slightly more expensive but its worth a look. Great site and I am sure there are a few things there I need.

on ebay search for# 330120602098 that is a 3/8 but he sell some in 3 parts all the same outside different bores. i have bought several items & have always been very satisfied. greg

Cueshark, thanks for the ebay link. I will bookmark it for later reading.

I don't know what the Lovejoy couplers from Enco are made out of, but they aren't plastic. Their Lovejoy website talks about powder metal presses. I can tell you they're ferrous. The couplers are not sold as a set - you have to order the parts separately. I use them on my CNC router to mate the 1/4" stepper motor shafts to 1/2" Acme rod. They work great. Now that I have my lathe, I'll turn the Acme rods to 3/8" with a flat for the set screw. I haven't seen them in metric, so you'll either have to bore out the 3/8" (.375) to accept the .3937" lead screw or turn down the screw to 3/8". Personally, I'd take digit's advice on boring them - that's a great idea using a drill to center it and changing bits. Part numbers are 990-4044 for the 1/4" ($1.97), 990-4045 for the 3/8" ($1.97), and 990-4042 for the Buna Spyder ($1.30). (Total $5.24 for the entire coupling as opposed to the eBay seller's $4.99 for just one end.) The Buna is rated at 26.3 in/lbs. They have a urethane spyder (Part # 619-3475) that is more expensive ($5.49) but is rated 39.4 in/lbs. I just bought the HF MiniMill last weekend and ordered end mills and collets from Enco last night. Orders more than $50 get free shipping with code WBJR7. Let us know how the CNC Conversion goes - it's next on my list of things to do too. Ed

Ed, The selection page for the lovejoy coupler at enco says its plastic. The moment i picked lovejoy as the brand, plastic is chosen for material. So not sure why. Maybe its a mistake on the webpage. But I have my concern should I buy from them and it turns out to be really plastic. And also I they don't seem to have different bore with the same OD diameter. Can you direct me to their site where you got your couplers in different bore diameter?

The part numbers you have quoted, which company sells them? Thanks

I rather not turn the leadscrew down if I have help it. But if I have to, I might just do that.

Can anyone advice me on how to turn a leadscrew or ballscrew that has threading right up to the end? I don't think I can place the screw inside the lathe chuck. The jaw might damage the thread.

[edo]

They're in the Enco on-line catalog - try this link and go to page 840.
http://www.use-enco.com/CGI/INPDFF

Third table on the page is Coupling Hubs. First column is the bore size, next column is the L050 series. The other series are larger and don't come in as many different bore sizes.

I assure you they're metal - I just stuck a magnet to mine. The product info page is wrong. Here's a link to them at Drillspot - they say they're made of Sintered Iron. The product number is exactly the same as Enco and is what's on the packages I got from them.
http://www.drillspot.com/products/62...upler-Body?s=1

Ed

[edo]

You may want to check your lead screw diameter again! I just measured the threaded portion that's sticking through the nut on the handwheel and it's 8mm (.314"). Isn't this the part you'd be connecting to the stepper?
Ed