Jig for drilling crankpin hole

bobwallison
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Re: Jig for drilling crankpin hole

Postby bobwallison » Fri Dec 06, 2019 6:40 pm

I have a few of the Proxxon tools, including the KT70 compound table. They are all well built and a pleasure to use. The KT70 is practically the same as the table on the mf70.
The mf70 looks like a super little machine, perfectly at home on a typical domestic workbench (unlike some other micro millers). I think it would be a bit limiting for drilling though, because the only way to move the bit up and down seems to be with the handwheel, at 1mm per revolution. Possible but slow - see 2:45 on Proxxons own video. It doesn't come with a chuck but I suspect that their item 28 941 would fit.
Proxxon offer a complete mill/drill system which seems to be the bees knees, but much more expensive at £500+.
Regards,
Bob

bobwallison
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Re: Jig for drilling crankpin hole

Postby bobwallison » Fri Dec 06, 2019 6:56 pm

PS
I was in Axminster's Nuneaton store yesterday, drooling over the Proxxon lathes and milling machines. They looked much better and more user friendly than Axminster's own-branded Chinese imports, but also about twice the price!
What particularly caught my eye, though, was the label on one of Axminsters lathes which told us that one division on the handwheel scale was "0.001 inch, 0.025mm". So thats an error of 2% (1 inch is actually 25.4mm, of course) - somewhat discouraging!
Regards,
Bob

nigelcliffe
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Re: Jig for drilling crankpin hole

Postby nigelcliffe » Fri Dec 06, 2019 7:06 pm

I'd caution against the MF70 as a drilling machine, because of the lack of lever feed. As a light cut milling machine its good, but it is light cuts only with quite small cutters(*). For some years I had, on loan, the rather heftier Cowell's small milling machine (and a very nice small mill it was!). But, as a drill that wasn't very good, because of the same issue - vertical feed was only by handwheel, no lever feed.

I have a friend who has the hand-held mains Proxxon 230E drill, plus the MB200 drill stand to fit the drill. For most vertical drilling jobs this is completely adequate, sensitive, and sufficiently accurate. Use of the fence on the drill stand allows drilling of holes in a straight line, which is usually about as complicated as things need to get.
Addition of one of the other optional clamping systems, and the 230E can be held as a fixed grinding/cutting disc machine.


Bob's comment on handwheels and divisions being reported as 0.001inch or 0.025mm is common. What should also accompany this is a description as to whether the lead and feed screws are metric or imperial. Then the buyer would know which measurement was accurate, and which approximate. Some lathe makers offer the buyer the choice of metric or imperial lead and feed screws. eg. Warco, show their small lathe as available in either Metric or Imperial


(* its a common starting place for a CNC machine - fit motor drives to each of the screws and let the computer drive the 0.05mm of movement for each cut pass, rather than the human getting bored at winding the wheels exactly one notch, then moving the table painstakingly slowly to take a small cut. But that tends to push the price up substantially for all the CNC conversion parts. ).


- Nigel

davebradwell
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Re: Jig for drilling crankpin hole

Postby davebradwell » Fri Dec 06, 2019 7:19 pm

You should be very careful milling in a drilling machine as the bearings are lighter and not designed to take a side load. Suggest check with Proxxon first. Also the chuck is usually just mounted on a taper so when milling is liable to come off which might be exciting at 8,500 rpm. There is a body of opinion (which included my mentors) that you shouldn't mill using a Jacobs chuck but many aren't troubled, including our own Terry B, I recall. See model engineers' forums. Speed range of drill might be restricting.

No, a mill without quill feed and lever would be a pain. I'll stick with my Bridgeport for now.

A mill is also useful for measuring and for setting things square, like frames. I've sen a mill with the "almost thous'" and it was a metric machine. Alarm bells rang when I saw the collar had 80 divisions. It's a very common machine. Not as bad as lathes where the handle turns the wrong way - potential suicide.

To advance the philosophy of toothpicks, try searching for toothpicks, instructions. It's probably just a generation thing.

DaveB

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Le Corbusier
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Re: Jig for drilling crankpin hole

Postby Le Corbusier » Fri Dec 06, 2019 7:27 pm

davebradwell wrote:You should be very careful milling in a drilling machine as the bearings are lighter and not designed to take a side load. Suggest check with Proxxon first. DaveB


I posted a milling machine with the question would it be accurate and able to drill effectively. I was not suggesting a drill to be used for milling. The consensus seems to be that the wheel feed would make it unsuitable .... though I am unsure if that is because it would be time consuming and therefore annoying - or because it would not be accurate or cut well for drilling?

davebradwell wrote:To advance the philosophy of toothpicks, try searching for toothpicks, instructions. It's probably just a generation thing.

DaveB

I assume this is a reference to Hitch Hikers Guide ... but not sure what it is commenting on specifically :?
Tim Lee

davebradwell
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Re: Jig for drilling crankpin hole

Postby davebradwell » Fri Dec 06, 2019 7:34 pm

Tim, I added the warning re milling because there was talk of using a co-ordinate table so it would be tempting. Slow wheel feed would just be a nuisance.

"Outside the asylum" reference to lighten a dark hour on this thread.

DaveB

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Le Corbusier
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Re: Jig for drilling crankpin hole

Postby Le Corbusier » Fri Dec 06, 2019 8:05 pm

davebradwell wrote:"Outside the asylum" reference to lighten a dark hour on this thread.
DaveB

Got the Douglas Adams part right anyway

“It seemed to me,' said Wonko the Sane, 'that any civilization that had so far lost its head as to need to include a set of detailed instructions for use in a package of toothpicks, was no longer a civilization in which I could live and stay sane.”


― Douglas Adams, So Long, and Thanks for All the Fish


It is very sad that the old skills are no longer taught at school ... my kids DT dept (note - not woodwork or metal work) limit their machines to disc sanders .... but they do have a laser cutter, a CNC cutter and a 3d printer :(
Tim Lee

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David Thorpe
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Re: Jig for drilling crankpin hole

Postby David Thorpe » Sat Dec 07, 2019 11:39 am

Tim, I suppose the decision rests on what the machine is to be largely used for. If you want a good drilling machine and think that it's possible but by no means certain that you might do some milling in the future, then the TBM220 and the KT70 might be preferable. If on the other hand you're definitely going to do some light milling and are prepared to put up with more awkward drilling, then the MF70 is obviously a consideration.

To confuse matters further, I've long wanted a decent handheld drill to replace my slightly wobbly Lidl device so for my recent birthday I received a package containing a Proxxon FBS 240E mains drill (described as a "precision drill/grinder/multitool), a Micromot MS140S drill stand, and an MS4 machine vice - https://www.germantools.co.uk/product/p ... kage-deal/ - which I thought was quite a good deal at £122. Advantage is that I can detach the excellent drill and use it alone as a handheld device. It's what Nigel's friend has, or very similar. For precision drilling I'd like something a bit more accurate than the MS4 which is very basic, and so this Christmas I'm to get a KT70 compound table which is designed to fit both the TBM220 and the MS140S and will I hope give greater accuracy with drilling - after that I'll risk some driving wheels with it!

DT

nigelcliffe
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Re: Jig for drilling crankpin hole

Postby nigelcliffe » Sat Dec 07, 2019 1:12 pm

If the MS104 is the same as other stands I've seen to that design, then the Proxxon MB200 stand is substantially better engineered stand. I've found MS104 style stands to be OK-ish, whereas the MB200 made me question whether there is any sense in buying the dedicated TBM220 pillar drill over the MB200+drill combination.

Whilst compound tables have their use, I'd put them in the "luxury most can live without" category.

I'm a bit spoilt with a workshop containing a fair bit of precision machinery (small lathe, mill and tooling to go with them), and easy access to larger machines if I ever need them.


- Nigel

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Le Corbusier
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Re: Jig for drilling crankpin hole

Postby Le Corbusier » Sat Dec 07, 2019 1:51 pm

I suppose the other option would be to go for a lathe. I understand that you can accurately drill and mill as well as turn albeit less conveniently?

Its just that the MF70 seems ideally suited to very fine work and would give both a drilling and a milling function in one?

Hey Ho ... decisions decisions :D
Tim Lee

davebradwell
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Re: Jig for drilling crankpin hole

Postby davebradwell » Sat Dec 07, 2019 5:08 pm

My warning about not milling in a drill didn't go very far then - please check with Proxxon first that the bearing are up to it.

DaveB

nigelcliffe
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Re: Jig for drilling crankpin hole

Postby nigelcliffe » Sat Dec 07, 2019 6:18 pm

Le Corbusier wrote:I suppose the other option would be to go for a lathe. I understand that you can accurately drill and mill as well as turn albeit less conveniently?

Its just that the MF70 seems ideally suited to very fine work and would give both a drilling and a milling function in one?

Hey Ho ... decisions decisions :D


Lathe as drilling machine ? Yes in theory. In practise, a small engineering lathe (eg. Sherline, Cowell, etc.) is somewhat awkward for most drilling jobs. Unless it comes with a pile of accessories to convert it to vertical operation. And, unless the lathe has a lever tailstock, you're still left with the lack of lever feed for drilling. Some D-bed clockmaker's lathes convert more easily to vertical drilling configuration.

MF70's are nice as mills, provided one accepts their very limited cutter sizes, the limited throat height (so tooling and work needs to be kept low on the bed), and the need to take very small cuts. There is a German company who sell replacement splindles, gear drives, etc.. to allow the machine to take ER11 collets (and thus cutters/drills up to 8mm). Euro100 for a spindle, and another Euro150 for the gearhead to alter cutting speed, it quickly becomes an expensive machine !
My experience of using machines with only a feed screw in the vertical axis (eg. MF70) is that they're awkward in practise to control drilling. One wants to bring the drill down to "almost" height quickly, then gently control movement. That is what a well balanced lever feed achieves.

Bear in mind the budget rule of thumb if buying a lathe or milling machine: to the basic machine price, add between 100% and 200% for tooling to accompany the machine.

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David Thorpe
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Re: Jig for drilling crankpin hole

Postby David Thorpe » Sat Dec 07, 2019 10:36 pm

nigelcliffe wrote:If the MS104 is the same as other stands I've seen to that design, then the Proxxon MB200 stand is substantially better engineered stand.

Sorry Nigel, it's not an MS104, it's an MB140/S. Can't say I've any complaints about it - in fact, I'm very pleased. It is of course a simple machine but it's solidly made of chromed steel and diecast aluminium and seems to do the basics well. The action is smooth and the drill steady and perfectly aligned, which is what I want. The MB200 has a swivelling head that permits bevelled drilling but I have no need for that (and if I did that can also be achieved, albeit slightly more awkwardly with the MB140/S).

If anything, Amazon users seem happier with the MB140, giving it an everage of four stars (65% five star, 8% one star), one more than they give the MB200 (only 28% five star, 35% one star).

DT

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Le Corbusier
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Re: Jig for drilling crankpin hole

Postby Le Corbusier » Sat Dec 07, 2019 11:08 pm

nigelcliffe wrote:
Lathe as drilling machine ? Yes in theory. In practise, a small engineering lathe (eg. Sherline, Cowell, etc.) is somewhat awkward for most drilling jobs. Unless it comes with a pile of accessories to convert it to vertical operation. And, unless the lathe has a lever tailstock, you're still left with the lack of lever feed for drilling. Some D-bed clockmaker's lathes convert more easily to vertical drilling configuration.

MF70's are nice as mills, provided one accepts their very limited cutter sizes, the limited throat height (so tooling and work needs to be kept low on the bed), and the need to take very small cuts. There is a German company who sell replacement splindles, gear drives, etc.. to allow the machine to take ER11 collets (and thus cutters/drills up to 8mm). Euro100 for a spindle, and another Euro150 for the gearhead to alter cutting speed, it quickly becomes an expensive machine !
My experience of using machines with only a feed screw in the vertical axis (eg. MF70) is that they're awkward in practise to control drilling. One wants to bring the drill down to "almost" height quickly, then gently control movement. That is what a well balanced lever feed achieves.

Bear in mind the budget rule of thumb if buying a lathe or milling machine: to the basic machine price, add between 100% and 200% for tooling to accompany the machine.


This thread has gone way of crankpin hole drilling :shock: ......But thanks for the thoughts Nigel - much appreciated.

My take away is that unless spending relatively big bucks - a jack of all trades approach will likely be master of none. :? ..... which inevitably leads back to the earlier suggestion of the TBM220 Bench Drill and KT70 Compound Table ;) Particularly as it has thumbs up from Phillip.

As I am already saving up for a lathe ... getting a decent bench drill is perhaps the way to go.
Tim Lee

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Tim V
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Re: Jig for drilling crankpin hole

Postby Tim V » Sun Dec 08, 2019 11:32 am

No one has mentioned the Unimat, which covers all the bases - precision vertical drill, small milling machine and lathe.

I've had mine about 30 years - a very good investment.
Tim V
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bobwallison
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Re: Jig for drilling crankpin hole

Postby bobwallison » Sun Dec 08, 2019 12:14 pm

Tim V wrote:No one has mentioned the Unimat, which covers all the bases - precision vertical drill, small milling machine and lathe.

I've had mine about 30 years - a very good investment.

Except that they are now only available secondhand? Even if one could be found at a sensible price it wouldn't seem wise for a novice machinist to start off with what could be a clapped-out machine.
I would love to be proved wrong - I am in need of a replacement idler pulley/bearing assembly for a Unimat 4 because my current one screams like a banshee.
Regards,
Bob

dal-t
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Re: Jig for drilling crankpin hole

Postby dal-t » Sun Dec 08, 2019 1:21 pm

Unimat 1 Metaline still available new (699 euros with tax in France) - plastic Unimat 1 with many parts in metal instead - but only secondhand Unimat 3s (not sure the downgraded Unimat 4 ever sold here).
David L-T

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Le Corbusier
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Re: Jig for drilling crankpin hole

Postby Le Corbusier » Sun Dec 08, 2019 1:42 pm

Tim V wrote:No one has mentioned the Unimat, which covers all the bases - precision vertical drill, small milling machine and lathe.

I've had mine about 30 years - a very good investment.


Do you have a picture of your set up ... I would be very interested. Also, it sounds like each element is effectively a separate purchase ... simply combined onto the one machine? ... so perhaps not really a 'jack of all trades' - or perhaps I am misunderstanding?
Tim Lee

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Tim V
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Re: Jig for drilling crankpin hole

Postby Tim V » Sun Dec 08, 2019 2:29 pm

Here you are. Mine is the Unimat 3.
IMG_0474.JPG


My original motor packed up with worn brushes, so I bought a new motor for it (seen on the lathe). Then I made an extra pole to support the old motor - by now fitted with new brushes (from a Hoover of some description) to create the precision vertical drill. I found I was always changing the machine around, so I now have two machines ready for use.

The lathe has a quick-change tool post. https://www.chronos.ltd.uk/product-cate ... he-unimat/

http://www.glue-it.com/wp/tools/lathes/emco-unimat-3/
Tim V
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Captain Kernow
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Re: Jig for drilling crankpin hole

Postby Captain Kernow » Sun Dec 08, 2019 4:30 pm

Will L wrote:I'm amused and a bit concerned that this appears to be a problem which is only soluble by the ownership of a decent drill press. Better not tell new members that until we got their membership free. More seriously, while I do admire the engineering skills many of you exhibit, I do think we might need to allow for methods that could be used by those who haven't got access to machine tools.

Quite and well said!

So what is the consensus for us poor souls who don't have access to these wonderful machine tools (lathes, vertical drills etc.), without which even most of these ingenious jigs appear to be out of reach?

Does the absence of a manufactured jig for sale mean that we are condemned to perpetual hit-and-miss bodgery? (or waiting for Ultrascales?).
Tim M
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Le Corbusier
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Re: Jig for drilling crankpin hole

Postby Le Corbusier » Sun Dec 08, 2019 4:56 pm

Captain Kernow wrote:
Does the absence of a manufactured jig for sale mean that we are condemned to perpetual hit-and-miss bodgery? (or waiting for Ultrascales?).


For my part I don't believe so.

As I suggested quite near the start ... a simple penny disc with a hole drilled for the axle and a hole drilled for the crankpin throw will get you an accurate position for the point of entry for the crankpins on all wheels. If you house a length of axle into a block of wood like Julian has done, drop the wheel over and then drop the simple jig over this, and endeavour to hand drill as vertical as possible, you will have a series of holes which guarantee the emergence of the crankpin at the same point on each wheel.

You can then use Allan Goodwillie's jig (posted earlier) to ensure that all the crankpins are set near as damn it vertical ... and you are good to go. :thumb

This is what I did on my Barney, and following adjustment with Allan's jig it is running nice and feely.
Tim Lee

nigelcliffe
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Re: Jig for drilling crankpin hole

Postby nigelcliffe » Sun Dec 08, 2019 4:57 pm

There are several mentions of hand-drilling arrangements to achieve vertical holes in the thread above.

There's a DIY option I wrote about 20-odd years ago (sorry for the 1990's standard of web images!),
http://www.2mm.org.uk/articles/fonly/fonlydr.htm
http://www.2mm.org.uk/articles/fonly/fonlypt1.htm

Whilst the ideas in the Fonly series might not look serious, the machines are capable of decent work. Minicraft drills are no longer available. For a modern version, you'd need to find a mini drill with decent bearings - I'd probably start by looking at a Proxxon.


Unimats - a mixed bag, with the name attached to machines ranging from excellent (eg. the "3" which Tim V shows) to hopeless. Only buy after doing some research.


- Nigel

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David Thorpe
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Re: Jig for drilling crankpin hole

Postby David Thorpe » Mon Dec 09, 2019 11:58 pm

Le Corbusier wrote:My take away is that unless spending relatively big bucks - a jack of all trades approach will likely be master of none. :? ..... which inevitably leads back to the earlier suggestion of the TBM220 Bench Drill and KT70 Compound Table


If this is the way you're going to go, I'd recommend that you get the MS4 machine vice at the same time.

DT


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