HHIP 3901-5038 ER-40 Collet Chuck, 132 mm Diameter x 42 mm Height

The ER-40 with 132mm diameter mounted up nicely to my Smithy 1220. It was a bit tight to Smithy's chuck mount so I mounted it in my 4 jaw chuck and lightly sanded the 132mm diameter to make a nice fit. The tapped holes are too big for the Smithy so I just through bolted it. Works great and the inside taper has a runout of only 0.0002" so very pleased.

It's perfect that it's affordable price. Actually you can find it for less else where. I picked this one cause it fits to make an adapter for harbor freight 7x10 lathe ( there are other lathes that use same spindle). It comes with the er40 wrench but you will need some kind of round rod (5/16"?) to hold the chuck when tightening or loosening the chuck. We'll see how it will work for my application. So far happy.

I saw a review that said, "It's a hunk of metal; hard to mess up" or something to that effect. There is a LOT that can be messed up on this piece. Concentricity, runout, accuracy, parallelism and surface finish all add up to make or break a piece of precision tooling. I didn't want to risk a bargain basement item not being accurate so I spent a little more and got a reputable brand. There are 3 holes in the edge of the chuck for a Tommy bar. Big plus! A 5/16" bar fit so an 8mm bar probably would also fit. It comes with a hook type wrench. The inside radius of the wrench is smaller than the OD of the ER40 collet nut so the wrench only contacts the nut at the notch and the other end of the radius. It looks like a good start to slipping off of the nut. Since the ER40 collets will be used on both the lathe and mill I'll be ordering a pair of the wrenches that have closed circle ends like https://www.amazon.com/uxcell-Collet-Spanner-Clamping-Non-slip/dp/B098JKMPG3/ref=sr_1_10?crid=27GW12BOWE1YL&keywords=er40%2Bwrench&qid=1701042827&sprefix=er40%2Bwrench%2Caps%2C101&sr=8-10&th=1. The whole point to me of using ER collets is the accuracy they offer. The collet chuck is very nice for the price. It has the usual issues of less than premium tooling. All of the drilled holes had sharp edges, quickly remedied with a Noga hand held countersink. The male threads for the nut looked perfect but to the fingers they were a little prickly. Literally two swipes with 320 grit emery cloth and they were smooth. The collet nut spins on very smoothly. I wasted no time getting it mounted on the lathe. I already had a backplate with a 72mm boss machined onto it so after a quick resurfacing the chuck was mounted. The screws required are M8x1.25 and with my backplate 35mm long would have been perfect. I used what was available; 40mm and they are about 3/8" too long but don't interfere with anything. I'll shorten them later. I immediately tested the runout with a dial test indicator inside the taper of the chuck and got almost no movement of the needle. There was so little that I would have to attribute it to the spindle bearings. That test completed, I snapped a 1/2" collet into the nut. The collet snapped in easily with a nice little click. Not having a test bar I chucked a 1/2" end mill into the collet, snugged it up and ran another runout test. The needle moved no more than .0002". I haven't made anything with the collets and chuck yet but have no doubt my accuracy should improve over the 5C collets I've been using.

Item secures collet and is accurate. Works very well.

ER40 100mm variant: Perfect fit for my mini-lathe with Little Machine Shop backplate adapter sku# 1692. Chuck inside taper TIR <0.002".

Zero runout at 1" and less than 0.0005" runout at 8" using precision round rod.

After machining a backplate with no discernible runout I found the chuck to have a runout of about .001 and when the collets are installed, just a tad little more. If you are looking to do really critical work you may want to look elsewhere and spend a bunch more money. I have no complaints as I received exactly what was advertised and would recommend it to the home shop machinist.

The fit and finish is very good. I adapted this to my lathe and have less than 0.001" run out. Been very happy with it so far. Only reason for 4 stars is I have a hard time giving items like this 5 until you use it and test it a lot. You really don't know how well it remains accurate. It also past the file hardness test.

I bought a blank adapter plate and machined it to fit my lathe spindle and then machined the other side to fit this chuck. It runs within 1/2 a thou. (0.0005" ) I was a bit disappointed by the wrench they supplied with the chuck. It is the wrong size in my opinion but it does sort of work. I had a more suitable one that came with another device so I use it instead.

Very hard to thread back on, really wants to cross thread.