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Member postings for Gene Pavlovsky

Here is a list of all the postings Gene Pavlovsky has made in our forums. Click on a thread name to jump to the thread.

Thread: Hobbymat MD65 quick release toolpost holders
18/10/2020 18:08:46

Alan,

I know it's an old post... Have you made the extra toolholder? Or did you find some other solution?

Cheers

--Gene

Thread: A Fabricated Small DIY Tool & Cutter Grinder - Joe in Swakopmund
01/10/2020 14:16:38

Joe, did you make any changes with regards to the motors cooling? I'm planning to make a small toolpost grinder similar to yours, my motor is significantly smaller (SunnySky X2216 III), I'm thinking about using a 40x40 DC fan for cooling.

How do you adjust belt tension in your designs?

I'm also wondering what kind of power connectors you're using between the ESC and the motor. It looks like a D-sub shell with some sort of RC connector installed inside (MR60?).

One thing I don't quite understand, both toolpost grinders have ER collet chucks, however I see some accessories with tapered shafts at the back. How are those mounted?

Did you machine the ER spindles (the inner, rotating parts) yourself, or are they straight shank ER collet chuck extensions like this one?

--Gene

Edited By Gene Pavlovsky on 01/10/2020 14:20:21

Thread: Milling spindle motor - AC or DC
01/10/2020 14:12:39

Thanks for your input, everyone. Joe's devices look very cool! His motors are significantly larger than the one I've got, but I guess for the small spindle I'm planning it should be enough.

30/09/2020 17:15:08

I've just finished reading the book about Spindles (Workshop Practice Series 27). I had a few questions in the process, which I was going to ask here, but had since forgotten :D

At the end of the book there's a section on mounting and driving the spindles, the author quite categorically states that we are going to use AC and not DC motors, without any explanation of the reasons. He suggests pilfering single-phase AC motors from e.g. a washing machine, using a 4-pole motor (~1450 RPM at 50 Hz) for the milling spindles and a 2-pole one (~2900 RPM at 50 Hz) for the high-speed grinding spindle.

I'm just wondering why DC motors are immediately dismissed?

I'm planning to start with building a small high-speed spindle, something like a more robust version of the Dremel rotary tool, either with the Dremel nose, or with an ER11 collet chuck.

I was looking at brushless RC motors, these seem to be small and light, yet powerful. They do need a special speed controller (ESC) and a DC power supply. Still, it seems to be possible to build a working system very cheaply. Here are the parts I've got so far, and what I paid for them:

$28.70 from eBay SunnySky X2216 V3 1250kv brushless motor

$11.14 from eBay a 40A Brushless ESC EDIT link removed see CofC 

Other parts I have from various places, some bought, some got for free at the local recycling center (people throw out all kinds of useful electronics, including complete PCs with a nice PSU inside):

SilverStone ST85F-P 850W computer power supply, up to 67A on the single +12V rail. A few load resistors on different power rails should be used to provide the minimum required loads, specified by the manufacturer. I wonder, though, if I'm going to be using only the +12V rail, do I need the load resistors on any of the other rails?

At 12V, this motor would spin at up to 1250*12 = 15000 RPM. From what I heard, speed control should be reliable within 10%-100% range, so if 1:1 gear ratio is used, the speed range would be 1500-15000 RPM.

Control box for adjusting the speed - should be easy to build. It needs an on/off button, a potentiometer for setting the speed, and should generate a PWM signal to feed to the ESC. Getting fancy, a 7-segment 4-digit display might be added to display the theoretical RPM (or even the real one if the spindle is going to be outfitted with a tacho). I'm going to pick one of the following things I have on hand: Arduino Nano, Pro Mini, bare ATmega328P or bare ATtiny85 MCU.

The motor is of the outrunner type (the body rotates), so it might be best to put it in an enclosure for safety, and use a 12V fan to force air through the enclosure to cool it down.

I would like to hear your thoughts on pros/cons of using a DC motor (and specifically a brushless RC motor). Here's my take:

I suppose that using a plain old single-phase AC motor is really simple, could be found cheap or free, and there are no extra things required, mounting it should be simple if it already comes with a mounting base. Cons - big and heavy, fixed speed.

3-phase AC motor and a VFD: motor could be found cheap or free or bought at a relatively reasonable price, VFDs are relatively expensive unless using a noname one from China. Some extra setup required. Motor is big and heavy. Mounting should be simple.

BLDC motor, ESC, DC power supply, homemade speed controller - more parts involved. Motors and ESCs (new) are affordable, a high-current DC power supply can be expensive, but if using 12V, a cheap or free computer PSU can be used. A custom speed control box has to be made, very basic electronics and MCU knowledge required (a few Arduino tutorials should be enough). Some custom mount would need to be made.

One thing I don't like about this setup is at such a low voltage - 12V, and high current - 30A (40A peak), the power wires (and the power supply) have all to be quite beefy. The shielded power cable I got for this project is thicker/heavier than the one connecting my (small) lathe spindle's motor and VFD.

Edited By JasonB on 30/09/2020 17:24:18

Thread: ER11 collets with 1mm range
09/06/2020 18:06:17

I don't think they're made in Germany, at this price point.

I did notice the 1mm step in the description, and also the generic photos (really annoying), but ordered anyway. At the moment I don't think I would have any use for the X.5 mm sizes. Hopefully the set will be really extra precision. I've already separately ordered 1/4" and 1/8" collets from China, supposedly high precision ones.

These Fahrion collets look very fancy, for my needs I don't think I need that sort of accuracy, but nice to know they exist.

I will follow the advice and not close down the collets too much (not over 0.5 mm), and will buy intermediate sizes if a need arises. The ER11 and ER20 sets were cheap enough that I think it made sense to buy in sets, they are also small and won't take too much space in storage. I will likely also make an ER32 collet chuck and buy individual collets only for the sizes I need.

Thanks everyone!

09/06/2020 15:17:07

I've just bought two sets of precision collets from SanTool in Germany - ER11 and ER20.

To my surprise, the ER11 set turned out to be 7 collets stepped 1mm, instead of 13 collets stepped 0.5mm.

The actual collets are marked 7-6, 6-5, ..., 2, 1 - suggesting their range is 1mm.

However, all the ER11 collet sets I've seen in other shops are 13 pieces, each piece having a 0.5 mm range.

I tried to find any info online about existence of ER11 collets with 1mm range, but couldn't.

So, is this really an incomplete set, with improperly marked collet sizes? Or did SanTool somehow manage to beat the competition and provide a superior clamping range in an ER11 collet?

Here's the product page

Edited By Gene Pavlovsky on 09/06/2020 15:17:23

Thread: Hobbymat top slide repair
02/06/2020 14:17:46

Heh, just goes to prove this IS a fragile part, not a great feat of engineering perhaps.

I can now see the clamps I'm going to make, although low profile they are not, and can't really see how it would be possible to make low profile.

02/06/2020 10:09:18

Wow, so many options! You guys are really a great bunch. I like Jason's single-piece clamp idea (and the CAD rendering), this would be less awkward to use compared to two separate clamps (which could rotate while adjusting)

02/06/2020 07:52:11

Bazyle, sounds a bit difficult for me - a guy with very little machining experience! I'm sure if I re-read your instructions 10 times, I would figure exactly what you mean, but so far I understand only half of it. A little drawing might help I'm not sure I would be up for this project, sounds like it would be better go get a little more skills first. E.g. I've never even milled in my life to this day (though I want to learn).

Teco Znojmo got back to me real quick with a quote, the replacement part is 54 EUR + shipping (another 20). I'm thinking to try the clamps solution first, and if I don't like that, get the replacement from Teco.

01/06/2020 16:39:21

Yes I'll post back when I solve the issue! Thanks again

01/06/2020 15:21:09

ega: I see what you mean now. Replacing the whole bottom wouldn't work, I'm sure. There's also a centering pin there on the bottom, I imagine hardened, which fits a matching hole on the cross slide.

I will go with the clamps solution, and if I hear back from one of the companies who might provide a spare part, will consider getting a new one if not very expensive.

Thanks everyone!

01/06/2020 13:13:51

Thanks guys, it's good to hear that the clamp solution is not that bad and can actually be good.

I will make sure to make the clamps look nice to remind me of my clumsiness/stupidity!

Bazyle, I don't quite get how I could make the clamps sit lower than the original screw solution. Well maybe 1 mm lower. Can you please make a sketch of what you mean?

01/06/2020 12:33:14

It's a fairly standard arrangement, as per the diagram below.

Please bear with me as I'm a beginner. I could bolt the toolpost directly to the cross slide, by making an appropriate spacer with holes in the right places. But how would that help mill away the broken-off area (without also milling away the other side)? I thought you were talking about using the lathe as a mill. I have the original Hobbymat angle plate, to which the top slide can be screwed to, serving as the vertical slide. But if I want to machine the top slide's base itself, I'd have to somehow clamp it horizontally directly to the angle plate at the right height, and use the cross slide traverse for milling, right? I could use an appropriate wooden block as a spacer and a couple of clamps to hold the base to the angle plate. Does this sound reasonable?

From what I understand, it's going to be a lap joint, right?

topslide_diagram.jpg

01/06/2020 11:53:31

Brian, thanks for your suggestions. I've e-mailed Essel Eng, Emco Machines, and Teco Znojmo - the manufacturer of the SU300, regarding availability/pricing of the spare part. The clamp you mentioned is too tall, but it really should be not a problem to make one. It would as well be good exercise to atone for my sin of dropping the topslide.

Hopper, I see your point about alignment difficulties of the silver soldering. And I guess the joint wouldn't be very strong because of lack of the gap for the solder to flow into.

01/06/2020 11:19:58

ega, do you mean the replacement would screw from the bottom (can imagine that), or from the side (more difficult to imagine)? In theory it could be possible. I don't have a mill, so machining off would probably have to be outsourced (unless I, as a beginner, just don't see the obvious way to do that in the lathe, without using the top slide as the vertical slide).

Hopper, I actually thought epoxy could work, but perhaps I'm wrong Is brazing/silver soldering out of the question?

For the clamps, I imagined something similar to these clamps: https://www.rcm-machines.com/en/machine-accessories/clamping/clamping/1-pair-clamping-kit-50-x-20-x-9-mm,-max.-m8/rcspw165

Could be easily produced by filing and drilling.

01/06/2020 10:05:20

Had an unfortunate incident involving my lathe's top slide and a concrete floor. Ironically, I've already bought some floor matting to prevent this sort of thing, but haven't installed it yet, wanting to do a proper organizing/cleanup first!20200529_122120_hdr.jpg

20200529_122340.jpg

Is this fixable?

Metal-filled epoxy, brazing (silver soldering)? I am waiting for silver soldering hearth and silver solder from Cup Alloys. But I only have a handheld MAPP torch from Rothenberger, and the base is quite heavy, not sure it would be enough heat.

A friend advised against welding as it would likely warp the part.

Another (ugly) option would be to just make a pair of clamps to hold the top slide down - similar to the sort used on a milling table.

If thinking about a replacement... I once saw a top slide on eBay for around 130 EUR. Or perhaps a replacement top slide base could be made to order.

Thread: Hobbymat MD65 fixed steady
05/05/2020 22:31:53

Thanks for the info Gerry. The pictures look very nice. I hope to get on with this project this year!

Thread: Lathe tool types
05/05/2020 12:43:32

Duncan, thanks, this looks very interesting indeed. I will start with regular style of tools and later will try a tangential toolholder. I had Mike's entire website already downloaded as there are a lot of interesting projects there!

Ronald, I do have a set of large diamond stones (usually for woodworking tools and knives), as well as hand-held diamond sharpeners, so I might try honing the carbide-tipped tools I have to just see how they differ from HSS in the way they cut.

05/05/2020 11:22:47

Thanks for a nice detailed comment Duffer. It's very thoughtful and indeed I wanted to eliminate one set of unknowns by having a reference tool which is expected to work out of the box. I did, though, get confused by your description of what LH and RH tools are used for (you mentioned "The RH knife is good for facing, LH for most ordinary turning". I was under the impression that most ordinary turning is done from right to left (towards the chuck), so wouldn't that be a RH knife such as this one? The definitions for LH/RH were suggested earlier in the thread: RH tool being one suitable to turn towards the chuck, LH one towards the tailstock. The roughing/chamfer tool sketch from Jason being a RH one. Please correct me if I'm wrong.

05/05/2020 09:58:52

Thanks Ketan. Good to know how these descriptions are written

I do have the book you mentioned, I've bought all of Harold Hall's books in this series, I like his writing style. I haven't got around to read it yet, thinking that I should focus on the Lathework course first. I already read it, next step is to re-read it while actually doing all the projects. But perhaps I should first read the chapter on lathe cutters in the sharpening book. I don't think I will be able to make the grinding rest like in the book yet, I do have a Veritas (a woodworking tools company) grinder tool rest which could probably be adapted to the task. I also found this compilation of articles advocating free-hand grinding without a toolrest, want to give this a try as well.

Edited By Gene Pavlovsky on 05/05/2020 09:59:17

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