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Member postings for Ian P

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

Thread: What is the way to put these holes in the right place?
08/10/2019 20:22:27

20mm cube and a name change, but I've just realised what the reason is!

Its to get round paying royaltieswink

Ian P

08/10/2019 19:51:45
Posted by Martin Connelly on 08/10/2019 19:39:29:

Dovetails are measured with cylinders to avoid problems like this. Do you have any silver steel or other ground rod that could be used against the angled face to allow more accurate measurement?

Martin C

Trouble with rods etc is that its fiddly holding everything in place, Balamy Blocks solve that.

Ian P

08/10/2019 19:48:31
Posted by JasonB on 08/10/2019 19:41:17:

Don't need to go wasting metal making L shaped jigs when you have a pair of Uncle Ketans blockswink

Or the little jig I mentioned above

45deg.jpg

Now there's the basis for a new product from Ketan.

If the block is precision ground to a 25mm cube (say) and the convergence of the two faces at 45 degrees is exactly on centre, then we have a 'Balamy Blocks'

I can think of other uses for the Balamy Blocks too.

Ian P

08/10/2019 19:42:06
Posted by JasonB on 08/10/2019 19:16:56:

If you make the cut so that the material is being cut in from the edge rather than cut out over it the burr should be minimal, and even if taken off with a stroke of a fine file will only make a thou or two difference which is less than you are likely to get eyeballing a scribed line.

I agree, a few though does not matter here but I wondered what the correct method of dimensioning this part would be if it was drawn for someone to manufacture.

I like you woodworking jig idea, on reflection I have made and used jigs like that previously but it slipped my mind for these parts.

Ian P

08/10/2019 19:33:42
Posted by not done it yet on 08/10/2019 19:17:09:

Any reason why you cannot drill and tap the holes before machining the ends to 45 degrees?

The tapped holes are normal to the angle face.

Ian P

08/10/2019 19:06:23

Michael, there has to be other holes anyway and a central one used as a reference when I set the part at 45 degrees on the mill table make good sense.

George, I was hoping to use a method that did not involve marking out as that just adds another two chances of variability creeping in (marking in the first place and following the marks in the second)

Jason, I basically use the acute edge as a reference but (whilst this part does not need micron precision) my concern was whether any machining burr would extend the edge and if so whether to remove it. I now think that if I use a new cutter and take a very fine finishing cut on the face there would be no perceptible burr. I have had an edge finder for years but this will be the first time I've used it!

Ian

08/10/2019 18:06:39

20191008_172533.jpgI have made one of these but I need to make several more.

The two end faces are at 45 degrees and have to fit closely between other faces on an existing manufactured product which has clearance holes for the three tapped holes in each end.

I can set the part up to mill and drill/tap each end but I am stuck knowing how to position them accurately. The sloping face is just over 21mm wide but the holes need to be offset slightly but its hard to measure to an edge which is not at right angles.

Ian P

Thread: Pulley material
08/10/2019 13:00:29

Thanks for the clarification. If you have run out of adjustment because of machining the original steel flanges then making new ones makes a lot of sense and using something that is less likely to corrode should solve the problem almost completely.

I used 'almost' because I suspect that having visible black dust (rubber off the belt presumably) indicates that considerable wear or some other action is taking place.

Belts do wear out which I suppose is indicated by the black dust, what is surprising in your setup is that it seems so severe. Since your application has to be robust it might be prudent to investigate further jsut so you have full confidence.

Is the belt doing a lot of work?
Is or was the belt tension correct?
Are the pulleys and shafts exactly aligned?
Is the belt the correct section for the pulleys?

Ian P

Thread: Recomend me a slitting saw to cut these fins
07/10/2019 14:42:57

Wow, that's a small engine, the head only appears to be about 10-12mm thick (unless I've got the wrong end of the stick)

Ian P

Thread: Pulley material
06/10/2019 11:57:33

I have seen scores of examples of pulleys manufactured using two back to back sheet metal pressings, but never seen one (of such a small diameter) pressed out of such thick material!

The only reason I can think of for it needing it to be heavy gauge is if the two halves are clamped together at the centre and have shims between them to adjust the belt tension. I am getting really curious about this 'small' two stroke engine that would have such a (relatively) expensive and robust cooling fan drive. I think of 50 or 100cc as being small but even at 250cc a cooling fan should not take a lot of driving and belt load would not be very high.

As has been mentioned the corrosion does not look severe enough to have any serious effect on belt life, in any event rough surfaces on the driving faces act to increase the grip (until worn off) and increase the amount of power that can be transmitted. For the rough surface to cause premature belt failure this belt must surely be driving a heavier load than just a cooling fan?

Regardless of all this I am still of the opinion that some other factors are involved in this installation, I mentioned car engine belt drives earlier as an example of pressed steel pulleys having a long life but that is just one example out of thousands where belts and especially pulleys have extremely long lifetimes.

Ian P

03/10/2019 08:42:14

If normal steel pulleys rust over one or two winters to the extent that they significantly shorten belt life then there surely there must be some other factors involved here.

Millions of vehicles have pressed steel pulleys and not all of them are in sunny climes and used all the year round, many get laid up over winter and presumably any rust that does form soon polishes off when the engine is running. A fan driven by a small 2 stroke engine should not impose a serious load on a V belt drive and I expect should last 20 years.

Are the pulleys in alignment? is the belt the correct section for the pulleys? is the engine totally exposed to weather conditions? probably other things that might be involved. Might help if you could post a picture.

Ian P

Thread: Issue 286 Spot drills
30/09/2019 19:23:10

Fragile to the point of not making it worthwhile to use one (might be a pun there)

My thinking used to be that a conical spot-drilled hole would be good so the drill (smaller diameter than that hole) must start concentrically within it, now I am not so sure.

If the following drill does not have symmetrical cutting edges then the drill will (bend) be pushed over sideways (even if the job has not moved off the same location), and as the drill moves downwards to the point where the tip make full contact and actually starts drilling it may then start off centre. Obviously can only happen with a badly ground drill but whilst that same drill might drill oversize in a centrepopped or shallow angle spotdrilled recess, at least it will stay on the same centre.

Ian P

Thread: Issue 286 - Bridgeport Article
30/09/2019 18:30:25
Posted by Ketan Swali on 30/09/2019 16:50:17:

Hi Andrew,

I can and do understand your frustration. Once something is in print, it feels

<snip>

If it is any consolation, your frustration is without financial loss. Hope that thought helps you get through your particular frustration. Keep writing as its all a good read. Life is too short for frustrations.

Ketan at ARC.

Ketan is right, a long time ago I thought that if I did not have 100% positive eBay feedback it would be a disaster, now though I realise life is too short to bother about things like that. I have read Andrews article and I found it really interesting and informative, so thanks.

Ian P

PS. I used eBay just as an example, probably not the best choice in Ketan's presence sad

PPS. I do have 100% good feedback

PPPS. I did once get neutral feedback (listed a brand new pair of Jeans on behalf of my wife, good brand and withe close up of the label etc) but buyer complained because 'they did not fit!

Thread: Issue 286 Spot drills
30/09/2019 18:14:18

I think two thirds of the article relates to lathe work and it does then focus on hole starting in general.

I have done a quick search to find 60deg spotting drills that could be used for lathe centre work but the only ones I found listed as 60deg were actually 120degree!

What I did stumble upon though has shown me that all along I have not been following the correct practice for using spotting drills prior to using a twist drill

Link to spotting drill usage article

Ian P

30/09/2019 17:12:49

Moved thread

Rather than start a new thread but since this one is morphing away from Andrew's specific article I thought I would make some comments on the current MEW 'Editors Bench' in praise of spotting drills.

I am a fan of spotting drills but I have not yet found (but I'm sure they must exist?) 60 degree versions that can be used (with a truncated centre or drilled clearance) with standard 60 degree centres. Neil mentions 90 degree ones which are fine for spotting but as the article starts with discussing centre drills it give the impression that they could be used to put centre holes in for lathe work.

Ian P

 

 

 

Edited By JasonB on 30/09/2019 17:56:35

Thread: Where to source bronze or brass plate
18/09/2019 23:00:16

I know you said you have changes the drawing now but if optimising material usage saves money the layout you show could be much improved (as long as its being cut with steerable blade like a fretsaw, but much more manly.

If these forks sit in grooves of gears that are close fitting on the shafts/splines then would just say 120 degrees of the circumferencial engagement rather than 180 be OK, would save even more material.

Ian P

Thread: Changed thread titles, what effect does it have?
17/09/2019 21:21:49

Any interesting lathe projects from beginners?

I wondered if anyone else found this recent thread title a bit misleading.

Technically (pedantly?) speaking, it seems that all the replies were off topic!

Ian P

Note to Moderator don't change in nowwink 2

Thread: Drill running off course
17/09/2019 15:41:24

The slocumb bits in your picture both look to be longer than ones I usually see, I have some very long centre drills which are useful occassionally but I have seen some of the larger sizes 3/8" / 10mm or so where the flutes from either ends would run into each other except for the fact that they are rotated 90 degrees. They might be rigid but dont seem designed for gripping in a drill chuck.

Ian P

17/09/2019 15:26:13

I wish they were longer!

Ian P

17/09/2019 14:26:36

+1 for using spotting drills

In spite of the pointed tip looking very vulnerable I have found they are actually quite robust and stay sharp for a long time, I've not worn one out yet in several years.

Most suppliers just seem to carry the 60 degree ones but other angles are available (Looks like Jason's picture shows a 90 and 120 versions)

Ian P

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