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Bench Top Honing & Lapping Machine

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Graham Meek20/01/2021 13:22:14
315 forum posts
227 photos

bench top honing & lapping machine.jpg


For some while now I have had an idea for a bench top mounted Honing and Lapping Machine. Anyone who has done the odd occasional lapping process will know the process is a bit hit and miss depending on the style of adjustment on the Lap, ie wedge or screw.

To date there has never been any calibrated design of adjusting the Lap. A recent experiments carried out by me and others, with a new design of Lap. Has spurred me on to design the tool above. Which in due course I hope to manufacture and write up.

Honing again is something that is done in the ME workshop. This usually takes the form of a spring loaded two or three pronged tool. I have never used one of these tools but have seen them on stands at Exhibitions. Being more used to using a Sunnen or Delapena Honing machine I thought the above lapping design could be adapted. While it will require dedicated hones to be made. Each mandrel has a range of bore sizes. The smallest mandrel designed so far will cover bores from 9.5 mm (3/8" up to 11.2 mm (7/16" diameter. It is intended to design a range of mandrels to cover up to 25 mm with sizes above this made as and when needed. The stones are bespoke to this design and use two different sizes per mandrel.

Like the hones each lap will have a range of sizes for each lap. Various lap sleeves can be made in each size range to accommodate varying grades of lapping medium. Because of the design of the sleeves these can be machined down to the next size when worn.

The constructor can therefore decide which system he or she would like, or of course they could make both.

More details to follow,




Edited By Graham Meek on 20/01/2021 13:23:04

Phil P20/01/2021 17:21:14
749 forum posts
181 photos


That looks very interesting indeed, my late father had a full blown Delapena machine and it was used quite a lot back in the day, the cylinders for my mill engine Agnes were done on it, so I know they are as good as I can get.

I will be watching this with interest.


bernard towers20/01/2021 19:05:54
106 forum posts
66 photos

Well done Graham something different and useful, also something to do with metal for a change. Look forward to updates.

Graham Meek21/01/2021 13:15:49
315 forum posts
227 photos

Thanks Phil and Bernard for the words of encouragement.

This has been another project like my Lathe Tool Honing Machine that has been kicking around in my Journal for some while. This current project has been mulled over for about 12 months. It started with the lapping mandrel shown below.

expanding lap assembled.jpg

expanding lap.jpg

I wanted to remove about 0.025 mm, 0.001", from the bores of my steam wagon. The O-rings were just a little too snug a fit.

A taper was turned on the end of an Allen grub screw such that one full turn advanced the balls 0.025 mm in total. Thus any fraction of a turn would give quite a precise control over how much cut was being applied.

What is not shown in the photographs is the partial split on the other side of the lap. The two balls in this design make the lapping sleeve barrel shaped. A newer trial has shown that three balls and three partial slits in the sleeve gives a better "feel" when lapping a bore. This therefore will be the final design of lap that I will include in the above machine design.

As the sleeves are interchangeable there is only need to make one mandrel per size range. The rest is taken care of by individual sleeves.

It was whilst working on the cylinder block of the steam wagon that I concluded this job would be easier if my body was not leaning over the lathe. Then the penny dropped that the adjustment could quite easily be made from the rear by a tapered pin up the inside of the mandrel. This then is how the idea developed, along with a lot of encouragement and discussions with John Slater.



Edited By Graham Meek on 21/01/2021 13:16:36

Ramon Wilson21/01/2021 14:37:14
1050 forum posts
205 photos

Hello Gray, long time eh? Hope you are well.

Though I can be fairly certain I won't be making a honing machine (just not enough time left) I think you've hit on a winner there.

Since we last spoke I've done quite a lot of successful lapping in building C/I model diesels where the piston and liner fit, though not so dimensionally important, the tolerances for a successful fit are. I've been using a copper wrapped type lap in many sizes which I think was first described by Len Mason. It works well, very well in fact, but has one drawback - it has to be withdrawn to be adjusted. Your lap design is a huge step forward in that respect and is earmarked for a future attempt.

I wondered though if you have witnessed any remote wearing on the surface of the lap at the point of contact of the balls or is that what you are referring to by saying the sleeve is barrel shaped?

The Mason type, though single point adjustment does bear along the whole length but as said has it's drawback.

Hope you are enjoying that retirement - doesn't half disappear quick though don't you find.

I'll look forwards to hearing more

Best Regards Ramon (Tug)

Graham Meek21/01/2021 18:00:18
315 forum posts
227 photos

Hello Ramon, (Tug)

It is good to hear from you, and yes it has been a long while now. Jean and I are both OK, being one of the vulnerable ones, we have both been shielding since the end of February last year. Long before we were required too.

We both hope everything is OK with you?

As regards retirement up until this last year in lockdown, I had wondered how I ever found the time to hold a job down. I do however miss not being at the Oncology unit doing my bit, especially now.

I have to agree with you as regards making the Honing Machine. I have struggled with the actual designing process just because of the current situation, let alone when it comes to actually making the machine. In order to complete another project it would be handy to have this machine. That is all that is spurring me on at the moment, plus I think it would be of benefit to others.

Having the lap larger at the centre is an advantage as it is easier to detect by "feel" if one end of the part is larger than the other. One old Patent sent down by John shows the laps with a very distinct barrel shape in the hole.

One real problem is trying to lap a blind bore. With this design the adjustment balls can be located almost at the end of the lap. The slits in this case would be open and confined to the end of the sleeve. This would allow the lap chance to lap just on the end. This is something where you are in the "Lap of the Gods" with a parallel lap, (sorry about the pun, it was not intended) .

From using the Sunnen and Delapena machines, honing stones are often manually modified in this way to concentrate the cutting action in one particular area.

The smallest lap so far designed for this machine, which is still minutely adjustable, is 4.75 mm diameter, this size does not use balls, and again the design can be adapted to do blind bores.

A couple of things I have forgotten to add earlier is the design incorporates an adjustable spring loaded ball clutch, similar to those on a Cordless Drill. This was something John said would be good to have and after thinking about it I had to agree with him. Especially as I would not want to put forward a design which could do someone an injury.

Another feature not shown is a spring loaded Spindle Lock. While a spanner flat is included just behind the collet closing Nut thread. It was decided to offer a hands free lock on the De-Lux model, should any constructor want one.

No doubt in due course we will have some 3D views which will explain things better.



Neil Lickfold22/01/2021 05:05:17
659 forum posts
102 photos

I have an older Delapena hone that I am rebuilding. I could make an adapter and make a lap conversion for it. Thanks for the ideas.


Graham Meek22/01/2021 11:51:11
315 forum posts
227 photos
Posted by Neil Lickfold on 22/01/2021 05:05:17:

I have an older Delapena hone that I am rebuilding. I could make an adapter and make a lap conversion for it. Thanks for the ideas.


Hi Neil,

That's what I like to hear people doing, taking an idea and then adapting it to suit their own needs.

Somewhere in my memory I seem to recall George H Thomas having something to do with the formation of the Delepena company. I know he was involved in two companies and that he started one company in Cheltenham. As he used to commute there from New Milton. Unfortunately the details escape me at the moment.



Michael Horner22/01/2021 12:57:14
215 forum posts
61 photos

Hi Gray

Would this be suitable for full size motorcycle conrod big ends.?

Taking them out to the next sized roller.

Cheers Michael.

Graham Meek22/01/2021 16:18:34
315 forum posts
227 photos
Posted by Michael Horner on 22/01/2021 12:57:14:

Hi Gray

Would this be suitable for full size motorcycle conrod big ends.?

Taking them out to the next sized roller.

Cheers Michael.

Hi Michael

A lot would depend on the diameter, the amount and type of material that is needed to be removed. For my purposes I was thinking along the lines of a 25 mm max bore with this 12v variable speed motor. The amount of material I would be looking to remove with this machine would be around 0.025-0.05 mm or 0.001- 0.002". This would be the amount I would leave in a bore during my toolmaking career, any more and the Resident Honer would throw a wobbly.

While this machine may be capable of doing larger sizes on an occasional basis. With a properly designed hone it might do 38 mm, but this is something that will need to be tested. There would be a trade off in that the metal removal rates would be that much slower due to reduced RPM. The top design speed is around 200 RPM. The limiting factor would be the current motor, the clutch may also need some heavier duty springs, or more of the current springs and balls. The fitting of a more powerful motor would extend the range. It is really a question of horses for courses. This initial design is intended for the ME user, but a scaled up version would have wider applications.

If your requirement is to do this operation on a regular basis then I would advise purchasing a second hand honing machine.



Edited By Graham Meek on 22/01/2021 16:20:24

Graham Meek25/01/2021 11:47:15
315 forum posts
227 photos

John Slater has been busy on my behalf converting my scribbles into something more realistic. We have left off the drive belts on purpose. The belts tend to hide some of the detail.

main frame-front view.jpg

main frame-rear view.jpg

main spindle assy.jpg

bearing locations & roller thrust beariings.jpg

motor mount.jpg

In due course we hope to share with you some 3D views of the Laps and Hones. I have yet to finalise the design on the hones so its down to me for holding things up.



Graham Meek28/01/2021 11:34:05
315 forum posts
227 photos

A view showing the deluxe Spindle Lock.

spindle lock.jpg

Plus a view of the standard Lapping mandrel with centralised adjustment ball bearings.

lap details.jpg

The sleeves of these being interchangeable for different diameters, (with-in the capacity of the mandrel), and different sleeve materials for each lapping media, (a sort of colour coding).



Edited By Graham Meek on 28/01/2021 11:34:47

Ramon Wilson28/01/2021 11:56:56
1050 forum posts
205 photos

Hello Gray,

Glad to hear you and Jean are well. yes

Looks like you are going to be busy with this in coming days. I too have a Delapena bench top hone - bought it at Ally Pally show quite a few years ago. Unfortunately it fell off the sack barrow getting it down those steps and damaged the dial and motor pulley. I eventually made a new pulley and rebuilt the dial but there it sits still waiting assembly. I found the results I got just lapping the IC cylinders have been as good as required so I've never felt the need to pursue it further.

Still looking forwards to seeing yours come to fruition though

Regards - Tug

Graham Meek28/01/2021 15:18:10
315 forum posts
227 photos

Hello Tug,

You were lucky to get a Bench Top Delapena. I have only used the stand alone version which would take up about 30% of my total workshop space. Bench space is also at a premium in my shop, hence why I make small machines that can be stored on a shelf when not in use.

Lapping is my preferred medium too, as my requirement to do work of this nature is very limited. Cost wise it is probably the most cost effective as regards materials, but possibly not time wise.

What triggered the inclusion of a honing version of this machine, was some information I was sent by John. This was concerning some 6BA grub screw adjustable hones made by Roy Amsbury for his President Loco. I saw how his design could be adapted to be used on the Lapping machine. It is always useful to have more than one option available in the home workshop.

In terms of design time getting these honing tools right has taken the Lion's share of my time. Initially two ball bearings were used to adjust the stone of each hone. This required some very precise stones, so it was quickly dropped for one central ball adjustment with spring loading. That led to the stone being in a carrier as the central pressure might crack the stone. This then requires some means of retaining each stone during the time the component is off the hone being checked. This leads on to the need to add two dowels to keep things parallel when the stone was in the free state.

Needless to say, God willing, I shall give these a trail in due course.

As regards to the manufacture of the machine that will have to wait. I have just had an hour in the shop this morning, and it is just too cold for me. My muscles started to complain after about a quarter of an hour. I still have to source some of the bought out items needed for the build so that will keep me busy in the meantime. Plus I have to write up the Lathe Tool Honing machine I made last year.

Take care,



Graham Meek31/01/2021 12:06:38
315 forum posts
227 photos

John has completed the 3D views for this project. The first shows a more detailed view of the Adjustable spring loaded clutch.


The second image shows the Hone assembly. The stone used in this version is 1.5 mm square and this particular design has a range of 9.5 to 11.2 mm diameter, 3/8" to 7/16" or there abouts. Each Mandrel uses the same design of stone holder. Individual stones could be made for each mandrel, or a few stones could be made and loaded into each mandrel as and when they are required. Currently the mandrels are designed to cover diameters up to 26 mm or about 1". Above this the design changes slightly and for me hones in this range of sizes would be made as and when they are needed.


The smallest adjustable lap so far designed is 3mm or 1/8" diameter.

I will keep you posted as to the progress on this project as the parts are made.



Edited By Graham Meek on 31/01/2021 12:09:03

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